Support for com.android.tools.build:gradle:1.4.0-beta6

[acleu]

For some features, the current Android Studio 1.4 needs the gradle build plugin in version 1.4.0-betax
(see http://android-developers.blogspot.de/2015/09/android-studio-14.html).
Switching to the current beta plugin (beta6) results in a MissingPropertyException:
groovy.lang.MissingPropertyException: No such property: bootClasspath for class: com.android.builder.core.AndroidBuilder
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:51)
at org.codehaus.groovy.runtime.callsite.GetEffectivePojoPropertySite.getProperty(GetEffectivePojoPropertySite.java:63)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGetProperty(AbstractCallSite.java:227)
at jp.leafytree.gradle.AndroidScalaPlugin.addAndroidScalaCompileTask(AndroidScalaPlugin.groovy:211)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
o...

According to groovy/groovy-android-gradle-plugin#61, in 1.4.0-beta2, AndroidBuilder.getBootClasspath() became AndroidBuilder.getBootClasspath(boolean).

Changing line 216 from
scalaCompileTask.classpath = javaCompileTask.classpath + project.files(androidPlugin.androidBuilder.bootClasspath)
to:
scalaCompileTask.classpath = javaCompileTask.classpath + project.files(androidPlugin.androidBuilder.getBootClasspath(true))

seems to fix the problem. Of course, a real solution would need to check the plugin version.