add .gemspec, remove jeweler dependency, reorganize files

It seems to require a .gemspec file in order to bundle install this gem (probably required by bundler for any gem).
Perhaps the gemspec is included on your dev machine but it's not on github because it's excluded by .gitignore? So I have added .gemspec.
I also removed jeweler dependency, as the jeweler gem has pretty much been replaced by bundler these days, and it may have conflicts with the gemspec I added.
I also moved the version.rb file to it's canonical location.
Cucumber and Rspec tests are green, but I haven't yet tried the gem within my application.
I note that your Rakefile says that MIT license applies, but the Readme points to the LICENSE.txt file, you may wish to resolve this discrepancy.
Oh yeah, one more thing... Thanks for the gem!
(oops, after generating the pull request, I noticed I didn't "squash" my commits, so you see 3 instead of 1... they all apply).