Fix whitespace flakes
Add trees to Admin interface and fix editing models

The previous URL definitions didn't start with a '^', and so any URL from
the admin interface with an id in the URL was picked up as being an
instance URL.
Merge pull request #64 from maurizi/master

Add trees to Admin interface and fix editing models
Run search when enter is pressed in a text field

I kept changing the filer value and hitting enter, expecting the page to
update.
Initial stab at making search performance acceptable

The main performance bottleneck was tree selection. This was solved
using an IN query:

```
trees = Tree.objects.filter(plot_id__in=plots)
```

This isn't really great, however, because this sort of join should
happen via a, uh, join. That said, this gives up the performance we need
to start working on search.

The other main performance helper was to only select trees that are
 useful for benefit calculations (have a species and a diameter).
Merge pull request #67 from jwalgran/topic/run-search-on-enter-key

Run search when enter is pressed in a text field
Add in boundary layer
Update geom column to 'the_geom_webmercator' for windshaft integration
Merge pull request #69 from ahinz/topic/boundary-layer

Topic/boundary layer
Merge pull request #68 from ahinz/fix/search-performance

Initial stab at making search performance acceptable