Ignore Gemfile.lock in .gitignore

Gemfile.lock will be built in each environment while the first time
run `bundle install`.
For another reason is 'puppet/indirector/hiera' is not in the puppet
3.4.2 which is current forced in lock file.
Require Bundler.setup to make rspec work

To load rspec-puppet which is downdoaded from github for testing, it
needs require 'bundler/setup' in order to load the bundler path.
Merge pull request #52 from TieWei/make-rake-spec-running

Make rake spec running