Fix deprecation warnings

Some more deprecation warnings:

    The ConfigurationContainer.add() method has been deprecated and is scheduled to be removed in Gradle 2.0. Please use the create() method instead.
    The TaskContainer.add() method has been deprecated and is scheduled to be removed in Gradle 2.0. Please use the create() method instead.
    The groovy configuration has been deprecated and is scheduled to be removed in Gradle 2.0. Typically, usages of 'groovy' can simply be replaced with 'compile'. In some cases, it may be necessary to additionally configure the 'groovyClasspath' property of GroovyCompile and Groovydoc tasks.