Fixes on CDH4 build / Maven improvements:
- remove usages of commons-lang (we use only commons-lang3, as defined in flink-runtime/pom.xml)
- Upgrade maven failsafe to 2.17 so that tests also fail if the test errors (exceptions during execution)
- added new build profile "docs-and-source" that creates javadocs and source attachments. These are usually only needed when releasing (--> speed up the build)
[FLINK-1046] Made sure that Client uses correct user-code class loaders.