Explicitly call exit on success

jclouds-karaf does not close BlobStoreContext or ComputeServiceContext
which caused some jclouds-cli commands to hang.  Work around this by
explicitly exiting.
Merge pull request #44 from maginatics/exit-0

Explicitly call exit on success
Basic build configuration for Travis [1].

[1] http://about.travis-ci.org/docs/