Remove Maven version detection

This reverts commit
43a2e68f62269d136e743b9878bcdf362924d4eb.

It seems that cppwrap works properly with Maven 3.x now, so we simplify
the build script to just use "mvn" all the time, as you would expect.
Deploy -sources JARs to Maven repository

For a number of reasons, it is very useful to have these sources JARs
deployed. For example, in Eclipse, you can right-click on a Maven JAR
dependency and choose Maven > Download Sources, and it will then
automatically download the sources JAR and link them for debugging.
Merge pull request #530 from melissalinkert/rebased/dev_4_4/cppwrap-maven-versions

Remove Maven version detection (rebased onto dev_4_4)
Merge pull request #531 from melissalinkert/rebased/dev_4_4/maven-sources

Deploy -sources JARs to Maven repository (rebased onto dev_4_4)