.gitignore Gemfile.lock per previous commit

Gemfile.lock was removed in a previous commit, should be ignored so it doesn't get committed again.

https://github.com/imathis/octopress/commit/06c04397053e46fe02fcecce589a2de76d21e160
Merge pull request #1617 from nickhammond/patch-1

.gitignore Gemfile.lock per previous commit
Delete Gemfile.lock

Follow-up to #1617
remove deprecated gems 'jekyll-page-hooks' and 'jekyll-date-format'
Merge pull request #1622 from raysrashmi/ry-updating-gems

remove deprecated gems 'jekyll-page-hooks' and 'jekyll-date-format'
Merge remote-tracking branch 'upstream/master' into themespace