Remove and ignore Gemfile.lock

* This generally should not be included in library code
  http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
Make gem compatible with Ruby 1.9

* The `require 'date'` is needed to include the Date#today interface.
  lol rubby
Merge pull request #1 from iamvery/remove-lockfile

Remove and ignore Gemfile.lock
Merge pull request #2 from iamvery/ruby19

Make gem compatible with Ruby 1.9