Better handle existing perms in add_default_permissions
Enhance units code for dealing with polygons and area

Allow specifying default units for plugins
Add square meters and square feet
Allow specifying a storage unit which is separate from the default display unit
Show area in edits page for polygon fields

Also move all audits display logic for geometry fields into audit.py
Show unit name abbreviations in Edits page
Show all mapfeatures on the edits page
Clean up recent_user_edits template
Clean up unit conversion dict
Rename typehead.html to species_typehead.html

I was making changes to this file and was worried about what I might break, so I grepped and found out it is only used for species partials. Since that is the case, I've given it a more explicit name so future developers need not worry that they are changing a very general template, as the name typeahead.html implies
Update text content

fixes #1099 on github.
Add support for creating users via API
Return "unauthorized" for HTTP requests

`instance_request` normally sends users to the login page. For the API
we really just want to return a 401
Merge pull request #1138 from steventlamb/topic/text_changes

Topic/text changes
Upgrade to typeahead.js 0.10.1.  Closes #120

This brings a few niceties:

We can access the typeahead datums directly, instead of getting
them through an undocumented .data() object

The option to tokenize client-side instead of server-side

The ability to sort suggestion results
Fixes #1130 and other problems caused by missing background image
Merge pull request #1132 from maurizi/topic/mapfeature-edits

Show all mapfeature edits
Fixes #1093: Fixed position footer, topper to content block is now optional
Fixes #374: Change text on edits, z-index fix on footer
Upgrade to azavea typehaead fork.

Adds back in showing default suggestions on focus if
minLength is 0
Merge pull request #1139 from azavea/topic/api/create-user-api

Add support for creating users via API
Merge pull request #1140 from mtedeschi/fix/1130/fix-background-image

Fix background images, footer, styling