Distribute nose source with the plugin, instead of the built lib.

This makes sure nose is built for the target platform, like python
2 or python 3.
Output stdout and stderr from shell task.
Make sure travis runs the devsetup and postinstall scripts.
Make travis do a sort-of integration test.

We test everything except downloading from npm, by creating a test
project, installing grunt-nose locally, and try running the task.