Update servers.rb to fix documentation.

The option is :except not :exception.
Update roles.rb to for proper documentation.

The last item in the `roles` argument, if it is a Hash, will actually pass as the options when filtering out the roles. This is extremely useful behavior and should be documented.
Git remote repository added to the rev-parse command.
Merge pull request #603 from MartialGeek/master

Git remote repository added to the rev-parse command.
fix for issue #578: update_asset_mtimes breaks in bash v4
Merge pull request #609 from planetio/master

fix for issue #578: update_asset_mtimes breaks in bash v4
Merge pull request #572 from johnbellone/patch-1

Update servers.rb to fix documentation.
Merge pull request #573 from johnbellone/patch-2

Update roles.rb to for proper documentation.