Gradle plugins migration to Gradle build

* Add gradle-tools subproject
* Add Gradle buildscripts to the related projects
* Remove the projects from the libraries pom.xml
* Move AndroidGradleWrapper.groovy to separate source root
* Changed artifact dependencies to project dependencies where needed
* Extract common configuration into commonConfiguration.gradle
* (convert functions to closures to be able to call them)
* Refactor DSL usage
* Replace `project.properties` with `findProperty`
* Unify Gradle wrapper between `libraries` and `gradle-tools`
(as a temporary solution, just made the wrapper files the same)

libraries/examples/kotlin-gradle-subplugin-example/build.gradle

@@ -0,0 +1,20 @@
+apply plugin: 'kotlin'
+
+repositories {
+    mavenLocal()
+    jcenter()
+    maven { url 'http://repository.jetbrains.com/utils/' }
+}
+
+dependencies {
+    compile project(':kotlin-gradle-plugin-api')
+    // Use this dependency instead when building apart from the other modules:
+    // compile "org.jetbrains.kotlin:kotlin-gradle-plugin-api:$kotlin_version"
+
+    compile "org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version"
+
+    compileOnly "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compileOnly "org.jetbrains.kotlin:kotlin-compiler-embeddable:$kotlin_version"
+    
+    compileOnly "org.jetbrains.kotlin:gradle-api:1.6"
+}