First commit for rubocop integration
Apply rubocop on all files

Github: #251
Rubocop

Some changes appeared on rubocop 0.26.0, fix them
Rubocop could not work with ruby lower than 1.9

Github: #251
Merge branch 'rubocop'

* rubocop:
  Rubocop could not work with ruby lower than 1.9
  Rubocop
  Apply rubocop on all files
  First commit for rubocop integration

Conflicts:
	lib/fakefs/file_system.rb
	lib/fakefs/version.rb
Fix rubocop offenses.