Remove logging settings from settings.py

The log settings are now configured in a templated local_settings.py.
Merge pull request #91 from jwalgran/topic/logging-setup

Remove logging settings from settings.py
Add favicon

Mostly to prevent 404 messages in logs when browsers automatically request
favicon.ico. I threw in Azavea's favicon.ico as a placeholder.
Merge pull request #93 from jwalgran/topic/favicon-redirect

Add favicon
Add PyCharm folder to .gitignore
Apply eco-benefits template server-side instead of client-side
DRY out search_tree_benefits()
Add tests for search_tree_benefits
Format eco-benefits more usefully

* Add label on each benefit (yet to be internationalized)
* Add unit on each benefit (yet to be locale-sensitive)
* Add number format string on each benefit
* Simplify template to use a loop
Rewrite SearchTreeBenefitsTests

Rather than testing returned eco-benefits values, test that:
* trees without diameter, species, or itree code are ignored for benefits calculations
* extrapolated benefits are larger than non-extrapolated benefits

Also, simplify extrapolation calculation and reformat its code a bit