Add Gemfile/Gemfile.lock and update bin permission

[agilecreativity]

Generally I think Gemfile/Gemfile.lock should be included as part of the ruby gem otherwise the bundle command will not working.

This PR include these two files and also the proper permission of the binary file on *nix system.

[agilecreativity]

Add default Rakefile to make it possible to install locally

• Fix the gemspec file to conform to the sensible default
• Add default .gitignore for ruby project file

With this changes, one can clone/run the installation locally e.g.

git clone git@github.com:selenium-cucumber/selenium-cucumber-ruby.git
cd selenium-cucumber-ruby
bundle
rake -T
rake install:local

If you have any question please let me know.