Some refactoring, fixes and updates

Delete extraneous files on the remote even if git is disabled, exclude the '.git' directory when git is enabled, change 'store_const' to 'store_true'.
Tell rsync what files to exclude, rather than what files to include

This should make it faster and more efficient on large directories.
Add flag to keep extraneous files on the remote (rather than deleting them)
Add Mercurial integration
Update README.md