if no folders are open in the current window, use the current file’s location to find Gemfile; do not search for Gemfile in parent directories as Bundler does that internally
* Extract more information about gems using a customized Ruby script instead of `bundle`
* Show gem summaries in the gem list
* Add links to open gem’s homepage and documentation pages  
* Refactor searching for Ruby executable a bit
* Instead of launching Sublime Text as an executable, use API commands to open gem folder in new window