Fixes download-heroku-backup script (bug 22)

Looks like heroku pgbackups changed their delimiter.
Updates gitignore to ignore local gems

Now I use rbenv I need to install gems locally to the application,
so this ignores them.

The change in bundler is to have a ~/.bundle/config containing

---
BUNDLE_PATH: vendor
BUNDLE_DISABLE_SHARED_GEMS: "1"