Update states/augeas.py. Fix index error.
Update states/augeas.py. Fix index error.

When specifying the test parameter, you get the error:

    Function: augeas.change
      Result: False
     Comment: An exception occurred in this state: Traceback (most recent call last):
                File "/usr/lib/python2.6/site-packages/salt/state.py", line 1533, in call
                  **cdata['kwargs'])
                File "/usr/lib64/python2.6/contextlib.py", line 34, in __exit__
                  self.gen.throw(type, value, traceback)
                File "/usr/lib/python2.6/site-packages/salt/utils/context.py", line 41, in func_globals_inject
                  yield
                File "/usr/lib/python2.6/site-packages/salt/state.py", line 1533, in call
                  **cdata['kwargs'])
                File "/usr/lib/python2.6/site-packages/salt/states/augeas.py", line 170, in change
                  ret['comment'] += ' in file {1}:\n'.format(context)
              IndexError: tuple index out of range


This change fixes the issues and provides better output.
saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt