ignore all .bundle folders and Gemfile.lock

Change-Id: Ib78461b98a15d81812d04bcdbc7e2dbd0320b979
Reviewed-on: https://gerrit.instructure.com/29508
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Raphael Weiner <rweiner@pivotallabs.com>
Product-Review: Raphael Weiner <rweiner@pivotallabs.com>
QA-Review: Raphael Weiner <rweiner@pivotallabs.com>