Fail on unintended Kernel.spawn.
Merge pull request #29 from jrafanie/fail_on_unintended_spawn

Fail on unintended Kernel.spawn.
Merge pull request #31 from brandondunne/remove_write_command_in_favor_of_File_#write

Removed Common.write in favor of File.write
Define errors in a single place
Ensure that the common specs verify the correct error is raised
Prevent yum tests from spawning