Upgrade Maven Compiler plugin to version 3.1

** Bug
    * [MCOMPILER-178] - can't specify -Xlint:-path option without violation of XML well-formness
    * [MCOMPILER-187] - incremental stuff detect changes even if nothing has changed means too much compilation
    * [MCOMPILER-190] - No compile errors with plexus-compiler-eclipse
    * [MCOMPILER-192] - No error reporting with forked compiler when Compiler includes non java files
    * [MCOMPILER-198] - Some parameters introduced in version 3.0 are annoted with since 2.6
    * [MCOMPILER-199] - Plugin 3.0 does not compile src/main/groovy if neither src/main/java nor src/main/resources folders exist

** Improvement
    * [MCOMPILER-188] - Add a flag to be able to disable incremental feature

** New Feature
    * [MCOMPILER-132] - Provide general "maven.compiler.main.skip" attribute