(maint) Add gem build and release rake tasks
(maint) Add gem build and release rake tasks

Without this patch there are no tasks to build the rspec-puppet gem
package or release the package to rubygems.org.  This patch addresses
the problem by adding the bundler tasks to build and release a gem.

tuxmea/rspec-puppet,electrical/rspec-puppet,johnmccabe/rspec-puppet,rbramwell/rspec-puppet,iankronquist/rspec-puppet,puppetlabs/rspec-puppet,fitpay/rspec-puppet,jeremy-asher/rspec-puppet,DavidS/rspec-puppet,rodjek/rspec-puppet,glauco/rspec-puppet,javiplx/rspec-puppet