Using the same configuration as Fog

closes #79
Following Fog cops usage.

The conventions is to follow github style guide.
Started fixing rubocop warnings in folder fog/core
Using #reduce instead of #each_with_object

The method #each_with_object is not implemented in  ruby 1.8.7.
Rolled back to #reduce and removed the cop to checks usage of
 #each_with_object to fix the build on tuby 1.8.7
Merge pull request #80 from zertico/rubocop

More Rubocop warnings fixed