Moved non-production code out of src/

Followon to https://rbcommons.com/s/twitter/r/868/

- Moved non-java targets into the 'examples' top level directory
- Moved projects used just for testing into the 'testprojects' top
level directory.
- updated docs and ci.sh accordingly

Testing Done:
CI is running (https://travis-ci.org/pantsbuild/pants/builds/32502524)

Bugs closed: 477

Reviewed at https://rbcommons.com/s/twitter/r/881/