Added 2 fixes.

Capistrano Version Used: 3.2.1

1. Fixed fetch_revision method for SVN. Was returning syntax error.
2. Fixed issue with changing the svn repo_path to a new branch. The default set-up of Capistrano and SVN will not work when changing the SVN repo_path to a new branch. Capistrano will do an update in the repo directory and not know about the changes in the new branch. I added a function called fetch_repo_url that will detect what branch is in the repo staging folder. I then modified the update method to do an SVN switch to the new branch if the repo_url does not match the currently downloaded version in the repo staging folder.