Extracted cleanup methods into cleanup.rb.

Will help with re-use in similar extensions.
Require and include cleanup.rb
Typos
Moved Cleanup to Utils

 * Renamed cleanup.rb to utils.rb
 * load utils.rb fri loader.rb file
 * include CommunityExtensions::STL::Utils in Importer class
Merge pull request #100 from jimfoltz/feat/extract-cleanup-methods

Extracted reusable utility methods into a Utils module.