JCLOUDS-720: Renames jclouds-cli artifact IDs

This PR fixes renames the `branding` artifact to `jclouds-cli-branding`, and the `runner` artifact to `jclouds-cli-runner`. It also updates the `.gitignore` file to ignore Mac OS specific `.DS_Store` files.

JIRA: https://issues.apache.org/jira/browse/JCLOUDS-720

This is dependent on PR #19 being merged first. This should *not* be backported to the 1.8.x branch due to the renaming of the artifact IDs.