Move exception over to format_call

This means we can catch typos in formatting and not let the reactor process die. Previously it would die with something like:
```
Process Reactor-6:
Traceback (most recent call last):
  File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/home/jacksontj/src/salt/salt/utils/event.py", line 686, in run
    self.call_reactions(chunks)
  File "/home/jacksontj/src/salt/salt/utils/event.py", line 672, in call_reactions
    self.wrap.run(chunk)
  File "/home/jacksontj/src/salt/salt/utils/event.py", line 707, in run
    f_call = salt.utils.format_call(l_fun, low)
  File "/home/jacksontj/src/salt/salt/utils/__init__.py", line 861, in format_call
    used_args_count
SaltInvocationError: run takes at least 1 argument (0 given)
```

Now you'll just get an error logged which looks something like:

```
[ERROR   ] Failed to execute run: <bound method ReactWrap.run of <salt.utils.event.ReactWrap object at 0x1f6f850>>
Traceback (most recent call last):
  File "/home/jacksontj/src/salt/salt/utils/event.py", line 708, in run
    f_call = salt.utils.format_call(l_fun, low)
  File "/home/jacksontj/src/salt/salt/utils/__init__.py", line 861, in format_call
    used_args_count
SaltInvocationError: run takes at least 1 argument (0 given)
```
De-dupe imports
Merge branch '2014.7' of github.com:jacksontj/salt into 2014.7