-Whitespace changes

-preparing to remove the author class
-history and revision no longer return an author as part of their result
-amended docstrings to reflect this

-added git-changed? in preparation for changing save-file! (it will no
 longer write contents out itself; that will be done by the user before
 calling. It'll just check if the file has changed, and run git-add +
 git-commit on it if it has)
-Removed author class
-All modifying functions now take optional author/email/message
-Re-organized cl-git-fs.lisp slightly
-Next up: need to make files strings rather than pathnames
-Fixed a typo bug in `delete-file!`
-repos are no longer pathnames, but rather strings
-README.md has been updated to reflect internals