Update api to return 409 when on existing username

Previous to this commit the new user registration endpoint would
crash when attempting to register an existing username. I modified
the register view function to first check if the username exists
and, if it does exist, return a 409 Conflict status code and a
detailed JSON-format failure message.
Merge pull request #18 from jwalgran/topic/dupreg

Update api to return 409 on existing username
Merge pull request #20 from ahinz/topic/search

Return only neighborhood info required
Fix password reset template layouts

I modified the password_reset_confirm and password_reset_complete to inherit
from registration/base rather than base so that they share a layout with the
other registration pages.

I also reworked the password_reset_confirm markup:

- Removed unnecessary <p> tags.
- Styled the validation error text so that it is red and appears next
to the appropriate field.
- Added "sub-label" detail text to the two field labels to match the
appearance of the registration page.
Merge pull request #21 from jwalgran/topic/pass-reset-layout

Fix password reset template layouts
Fix benefit to dict conversion in API

A None value was creeping into a calculation because of an if check on
a numeric function parameter

  if not dollar:

This will be true when dollar is None _and_ when dollar is 0.0 so I made
the if condition more explicit

  if dollar is None:
Merge pull request #23 from jwalgran/topic/eco-benefit-api-error

Fix benefit to dict conversion in API
added v1.2 release notes gist link to readme
Merge pull request #24 from azavea/andrewbt/topic/add-release-notes

added v1.2 release notes gist link to readme
Sort neighborhood list by state, county, and name

The 'geographies' view, on which this simplified view is based
sorts the neighborhoods alphabetically. We do not want to loose
this sorting in the simplified list.
Merge pull request #25 from jwalgran/topic/sort-hood-list

Sort neighborhood list by state, county, and name
Don't do zipcode validation

Zipcode is a hidden field populated via the geocoder.
Previously it was using a USZipCodeField to validate that
the zipcode was correct.

However, this prevents zipcodes in the UK from working
properly. Since we don't actually provide any references
to change the zipcode this error message is useless.
Fix file naming when uploading tree photos through the API

The previous version of the add tree photo API assumed the image was a PNG and
saved the file with a .png extension. This update uses the Content-Type header
to set the file extension.
Merge pull request #28 from jwalgran/topic/tree-photo-api-ext

Fix file naming when uploading tree photos through the API
Update data model with new fields

Add two new fields:
 * A choice-based field for pests
 * A URL field for each tree
Merge pull request #30 from ahinz/v1.3

Update data model with new fields
Inject i18n support for eco benefit values

Add a new param to the tm object:
    ``benefitUnitTransformer: function(k,v)''
This function returns ``v'' untouched by default but allows
a skin (in map.js) to update the and transform the values

Additional US->UK conversions were added as tags:
gal2litres
lbs2kgs

Note that $->£ is done via the database (conversion factors
are in £)
Merge pull request #31 from ahinz/topic/unit

Inject i18n support for eco benefit values
Add pests to the add form
Merge pull request #32 from ahinz/topic/forms

Add pests to the add form