Remove unused zones function. Fixes #128.
Add URL tests

We want to test that every URL succeeds (200) or fails with bad data (404).
We now have such URL tests for our "root" URLs (defined in opentreemap/urls.py) as well as our "app" URLs defined in:
    ecobenefits/urls.py
    geocode/urls.py
    treemap/urls.py

I did not add tests for URLs defined in:
    api/urls.py
    registration_backend/urls.py

Notes:
* I removed a few existing URL tests from other test files and added simplified versions to treemap/tests/urls.py
* I removed the assertTemporaryRedirect() helper and used django assertRedirects() instead
* treemap.views._plot_hash() now raises a 404 if instance lacks plot
* treemap.views.boundary_to_geojson() now takes an instance argument and raises a 404 if instance lacks boundary
Tweaks after code review
Merge branch 'url-tests'

Conflicts:
	opentreemap/opentreemap/urls.py
Allow empty eco benefit searches

When the initial page loads and shows all trees we need to calculate
the eco benefits for all trees. Previously, empty queries were returning
blank results or raising an error if the search query was {}
Merge prototype markup into templates

I pulled markup out of the files in /prototype and stitched it into
the existing templates.

While the templates are being rebuilt I created an instance_base.html
as a DRY place to build content that depends only on the instance.

The eco-benefit search returns markup for both the number of matching
trees and the actual benefits, but these two data sets are shown in
different places on the template. My solution uses jquery to pull the
markup apart and insert it into the appropriate DOM locations.

I did not bring over holder.js because it is a dev-only dependency and
adding libraries into our JS build process is non-trivial. I replaced it
with a static tree image.

In a future commit the login and registration forms need to be properly
subclassed to add additional styling and fields.
Remove lint
Merge pull request #140 from ahinz/fix/128/remove-zones

Remove unused zones function. Fixes #128.
Merge pull request #144 from jwalgran/topic/prototype-to-templates

Prototype markup to templates