Spelling, grammar, and consistency in spec/other/

  Fixes mistake in gems_spec.rb wording
  Fixes mistakes in git_spec.rb wording
  Removes empty line at end of class in source_spec.rb
  Fixes spelling/grammar in other/binstubs.spec
  mri -> MRI in other/binstubs.spec to be consistent and correct
  Fixes verb tense agreement in other/check_spec.rb
  Grammar fixes in other/clean_spec.rb
  Removes empty line at end of other/exec_spec.rb
  Removes empty line at end of other/init_spec.rb
  Removes extra empty lines at beginning and end of spec/other/outdated_spec.rb