Removed features settings: don't work when building with mvn.

The documentation actually says so:

 Note: Tycho's support for the target definition file format is limited:
   - The location types "Directory", "Installation", and "Features" are not supported.
   - The selection on the Content tab of the Target Editor is ignored,
      i.e. it is not possible to de-select individual bundles for the
      Tycho target platform.
   -  The option "Include source if available" is not supported.

http://wiki.eclipse.org/Tycho/Target_Platform#Target_files

This is probably because all of these select from the installed IDE or
somewhere else on local disk on the computer where the IDE is running,
none of which can be assumed to be present on a continous integration
build server.
Added JDT plugin development resources to get JUnit bundles for modeler.test.