Add OMEMO support

This commit adds the modules smack-omemo and smack-omemo-signal.
smack-omemo is licensed under the Apache license like the rest of the smack project.
smack-omemo-signal on the other hand is licensed under the GPLv3.
Due to the fact, that smack-omemo is not of much use without smack-omemo-signal,
the OMEMO feature can currently only be used by GPLv3 compatible software.
This may change in the future, when a more permissively licensed module becomes available.

Fixes SMACK-743.

build.gradle

@@ -40,7 +40,11 @@ allprojects {
 		// build, causing unnecessary rebuilds.
 		builtDate = (new java.text.SimpleDateFormat("yyyy-MM-dd")).format(new Date())
 		oneLineDesc = 'An Open Source XMPP (Jabber) client library'
-		javadocAllProjects = subprojects - project(':smack-integration-test')
+		integrationTestProjects = [
+			':smack-integration-test',
+			':smack-omemo-signal-integration-test',
+		].collect{ project(it) }
+		javadocAllProjects = subprojects - integrationTestProjects
 		// A dirty hack used for Gradle's jacoco plugin, since is not
 		// hable to handle the case when a (sub)project has no unit
 		// tests. :-(
@@ -56,6 +60,7 @@ allprojects {
 			':smack-resolver-dnsjava',
 			':smack-resolver-javax',
 			':smack-resolver-minidns',
+			':smack-omemo-signal-integration-test',
 		].collect{ project(it) }
 		projectsWithUnitTests = subprojects - projectsWithoutUnitTests
 		androidProjects = [
@@ -67,11 +72,17 @@ allprojects {
 			':smack-sasl-provided',
 			':smack-extensions',
 			':smack-experimental',
+			':smack-omemo',
+			':smack-omemo-signal',
 		].collect{ project(it) }
 		androidBootClasspathProjects = [
 			':smack-android',
 			':smack-android-extensions',
 		].collect{ project(it) }
+		gplLicensedProjects = [
+			':smack-omemo-signal',
+			':smack-omemo-signal-integration-test',
+		].collect{ project(it) }
 		androidBootClasspath = getAndroidRuntimeJar()
 		androidJavadocOffline = getAndroidJavadocOffline()
 		junitVersion = '4.11'
@@ -350,14 +361,6 @@ subprojects {
 						developerConnection 'scm:git:https://github.com/igniterealtime/Smack.git'
 					}
 
-					licenses {
-						license {
-							name 'The Apache Software License, Version 2.0'
-							url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
-							distribution 'repo'
-						}
-					}
-
 					developers {
 						developer {
 							id 'flow'
@@ -387,8 +390,17 @@ subprojects {
 	}
 }
 
-// No need to ever clirr smack-integration-test
-project(':smack-integration-test').clirr.enabled = false
+// There is no need to ever clirr integration test projects and the
+// smack-repl project.
+configure(integrationTestProjects + project(':smack-repl')) {
+	clirr {
+		enabled false
+	}
+}
+
+// Disable clirr on omemo modules
+project(':smack-omemo').clirr.enabled = false
+project(':smack-omemo-signal').clirr.enabled = false
 
 subprojects*.jar {
    manifest {
@@ -396,6 +408,49 @@ subprojects*.jar {
    }
 }
 
+configure(subprojects - gplLicensedProjects) {
+	checkstyle {
+		configProperties.checkstyleLicenseHeader = "header"
+	}
+	uploadArchives {
+		repositories {
+			mavenDeployer {
+				pom.project {
+					licenses {
+						license {
+							name 'The Apache Software License, Version 2.0'
+							url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
+							distribution 'repo'
+						}
+					}
+				}
+			}
+		}
+	}
+}
+
+configure(gplLicensedProjects) {
+	checkstyle {
+		configProperties.checkstyleLicenseHeader = "${project.name}-gplv3-license-header"
+	}
+	uploadArchives {
+	repositories {
+		mavenDeployer {
+			pom.project {
+				licenses {
+					license {
+						name 'GNU General Public License, version 3 or any later version'
+						url 'https://www.gnu.org/licenses/gpl.txt'
+						distribution 'repo'
+					}
+				}
+			}
+		}
+	}
+}
+
+}
+
 configure(androidBootClasspathProjects) {
 	compileJava {
 		options.bootClasspath = androidBootClasspath
@@ -436,6 +491,10 @@ task integrationTest {
 	dependsOn project(':smack-integration-test').tasks.run
 }
 
+task omemoSignalIntTest {
+	dependsOn project(':smack-omemo-signal-integration-test').tasks.run
+}
+
 def getGitCommit() {
 	def dotGit = new File("$projectDir/.git")
 	if (!dotGit.isDirectory()) return 'non-git build'