Clone and Fetch Updates

This version of mepo adds and changes the following.

Adds

• mepo fetch can now use --tags and --prune
• mepo clone can now run mepo init for you if not done explicitly
• mepo clone URL will do a git clone URL/cd/mepo init/mepo clone all in one shot
• Better handling of hashes. components.yaml will now accept hash: a la tag: and branch:

Changes

• mepo init and mepo clone have a slightly different interface if using a different yaml file. Since the ability of clone to use a URL, to pass a different yaml file, needs to be done with a flagged option: --config yamlfile

Fixes

• mepo status won't crash if a repo is not on a tag or branch