Upgrade to Maven Compiler plugin 3.8.0

** Bug
    * [MCOMPILER-311] - NPE when --patch-module is used
    * [MCOMPILER-321] - Problematic Java 9 modules are silently ignored
    * [MCOMPILER-332] - Java 10 not supported
    * [MCOMPILER-338] - Build Issue based on MCOMPILER-192 IT
    * [MCOMPILER-342] - Unsupported class file major version 55
    * [MCOMPILER-343] - Tests fail to compile in modularized project due to wrong module descriptor path being passed to plexus-java

** Improvement
    * [MCOMPILER-313] - Support mrjar dependency with module descriptor only in META-INF/versions/x 
    * [MCOMPILER-323] - Support multi-release jars
    * [MCOMPILER-335] - Update default source/target from 1.5 to 1.6
    * [MCOMPILER-341] - Compile module-info.java files located in test sources

** Task
    * [MCOMPILER-336] - Dependency that should be on modulepath sometime put on classpath
    * [MCOMPILER-344] - Deprecate <optimize> flag
    * [MCOMPILER-350] - Add GitHub Documentation

** Dependency upgrade
    * [MCOMPILER-324] - Upgrade parent to 31
    * [MCOMPILER-351] - Upgrade maven-plugins parent to version 32
    * [MCOMPILER-352] - Upgrade maven-shared-utils to 3.2.1
    * [MCOMPILER-353] - Upgrade plexus-compiler to 2.8.4