Applied fixes that allow tests to pass again.
Added exec command to homesick.
Merge pull request #97 from JCook21/exec

Added Exec command
Replace any system calls in lib that don't use git with calls to FileUtils
Replace a system call in the spec helper
Start using rugged for commands that don't need to show git output
Use Rugged instead of the ` syntax for shell calls
Use rugged instead of system in the spec helper