Improve test coverage

* Added aggregator to the list of modules being tested
* Improve coverage to 100% in all modules except search_models (which I didn't undestand well enough) and aggregator (which I didn't get time for)

If acceptable, I think this closes #115 for now.

/cc @calebsmith 

Final result is:
```
 Unit Test Code Coverage Results
----------------------------------------------------------------------
Name                             Stmts   Miss  Cover   Missing
--------------------------------------------------------------
raspberryio.aggregator               0      0   100%   
raspberryio.aggregator.forms        10      0   100%   
raspberryio.aggregator.models       97     45    54%   50, 55, 70-92, 109, 112, 116-152
raspberryio.aggregator.utils         3      0   100%   
raspberryio.aggregator.views        45     30    33%   15-16, 36-44, 54-67, 77-84, 94-98
raspberryio.project                  0      0   100%   
raspberryio.project.forms           68      0   100%   
raspberryio.project.models          98      0   100%   
raspberryio.project.utils           45      0   100%   
raspberryio.project.views          128      0   100%   
raspberryio.qanda                    0      0   100%   
raspberryio.qanda.forms             27      0   100%   
raspberryio.qanda.models            41      0   100%   
raspberryio.qanda.views             57      0   100%   
raspberryio.search                   0      0   100%   
raspberryio.search.models            8      0   100%   
raspberryio.search.utils            42     10    76%   44-46, 64-67, 70-72
raspberryio.search.views            33      0   100%   
raspberryio.userprofile              0      0   100%   
raspberryio.userprofile.forms        9      0   100%   
raspberryio.userprofile.models      18      0   100%   
raspberryio.userprofile.views       59      0   100%   
--------------------------------------------------------------
TOTAL                              788     85    89%   
----------------------------------------------------------------------
```