this commit fixes 2 problems:

-there was a trailing comma in the clock module that would interact badly with i3pystatus & i3bar; i3pystatus seeing the comma would generate the json ** full_text : ["13 september"] ** and then i3bar would only display the last module (one may have to check for i3bar robustness). resulted in having only the clock module displayed
-the 2nd problem was with the alsa module when setting the volume to a number < 0 or >100 then the pyalsa bindings would generate the following error in .xsession-errors
```
    target_module.on_click(command["button"])↲
  File "/home/teto/i3pystatus/i3pystatus/core/modules.py", line 31, in
  on_click↲
      self.on_upscroll()↲
        File "/home/teto/i3pystatus/i3pystatus/alsa.py", line 95, in
	on_upscroll↲
	    self.alsamixer.setvolume( vol + self.increment)↲
	    alsaaudio.ALSAAudioError: Volume must be between 0 and 100↲
```

I also improved PEP8 compliance in 2/3 places