Fix delete auto-merged branch bug.
Fix delete auto-merged branch bug.

Problem:

- The second push command (to delete the remote pr branch) in
  travis-auto-merge.sh isn't using the personal access token, and fails
  with:

  remote: Invalid username or password.
  fatal: Authentication failed for 'https://github.com/forerunnergames/fg-tools.git/'

Solution:

- Put the personal access token in the URL for the remote 'origin'
  (using 'git remote set-url'), so that any command interacting with
  'origin' will succeed. This also prevents having to specify the URL for
  both push commands, which increases readability & eliminates
  duplication.

forerunnergames/fg-tools,forerunnergames/fg-tools