model/scm: fix incorrect reporting of pull from remote git repo

In issue #327 it was reported that the pull of a remote git repo causes the
following inaccurate journal entry:
"committed via Kallithea into repository"

The problem is caused by the following flow:

1. pull_changes calls _handle_push for git repos, passing
action='push_remote'.

2. _handle_push calls _handle_rc_scm_extras, but does not pass 'action'

3. _handle_rc_scm_extras uses a default value of 'push_local' for action.

4. The action string 'push_local' will result in the mentioned journal
entry, via action_map in action_parser() (kallithea/lib/helpers.py).


To get a more accurate log entry, _handle_push should pass the action that
it got from pull_changes. In that case, the log entry will become
"pulled from remote into repository"