Nrh/janitor

Hi!

I'm hoping to make a few enhancements to vlad-push in the near future that we've been wanting at work.  In prep, I though it might be good to do some minor janitorial work.  In this PR:

- Switch bundler source to http to address bundler warning about security
- Update how to a version that support markdown
- Switch the README to Github flavored markdown

Please let me know if there's anything that you would like me to address.

Thanks!

-n