Extract modules to Gemfile.

Support using bundler, etc.
Add gitignore for lock file.
Merge pull request #16 from pnasrat/use-gemfile

Extract modules to Gemfile.
Merge pull request #19 from erjohnso/master

Updated to support GCE API v1beta16 (gcutil-1.10.0)
GCEv1 and adding master, start-service metadata vars