JarsignerTask and Keystore Target

This adds a new Keystore target and a JarsignerTask. It outputs
the finished apk, which can be verified by pointing it at the sample
code and installing the apk it outputs.

Pants can now output debug and publishable release builds.
The release keystore is removed from version control,
although we will be layering another level of protections
with the release keystore handling in the future.

This bundles an (insecure) debug.keystore, which is scheduled
to be removed soon once we add in the KeytoolTask.

Testing Done:
CI.sh passes.
Travis passes [0]

[0] https://travis-ci.org/pantsbuild/pants/jobs/32476705

Reviewed at https://rbcommons.com/s/twitter/r/883/
Properly order resources for pants goal test and pants goal run.

Fixed a problem with goal run and test for resources being put on the classpath in the
wrong order when multiple resource paths contain the same resource path.

Added a project with resources that collide and an integration test to prove
that resources are bundled and added to the classpath in the right order.

Note that the JVM tests will still fail if all run together with

   pants goal test maven_src/resource_collision::

because pants runs all the tests in the same junit test runner instance.