Fix Bitbucket API access

Previously for Bitbucket repos, the username and
the repo owner were assumed to be the same. This
is fixed by storing bitbucket_repo as "owner/
repo", and making sure bitbucket_api is only used
for authentication.

This change breaks all previous Bitbucket repo
configurations.
Merge pull request #107 from rogerso/fix-bitbucket

Separate username from repo owner name for Bitbucket API access