Add feature gates where appropriate
Use single species table with instance and otm_code

The InstanceSpecies join table was never implemented. Abandoning the
initial design of using a join table to link instances to a master
species list:

  - Allows map owners to have full control over their species list
  - Keeps species query logic simpler
  - Allows for UDFs on instance species

As of this commit the species rows no longer have an itree code.
Storing an itree code with the species is not correct, because the
specific itree code used for a species depend on the climate region in
which the tree is located.

The "otm_code" column (renamed symbol column) is now a unique identifier
for a species the lookup dictionary in ecobenefits/__init__.py links
these otm codes to itree codes by region. This mapping was based on the
data from http://www.itreetools.org/streets/resources/Streets%20Species%20Codes.xls

The otm_code field was seeded with USDA code values, but we are not
guaranteeing they will always match. We are creating our own set of
species identfiers that we can change if and when we need to.
Add a list of species dictionaries to treemap

This is our master species list used to generate Species rows when
creating instances. This was derrived by mergeing all the regional
itree streets species lists then deduplicating and cleaning the result
so that each otm_code is associated with a unique combination of
species, genus, cultivar, and other values.

The source CSV is included along with the shell script used to transform
it into dictionary literals. It is easier to make edits to the species
list by editing the csv then regenerating the JSON.
Style create a map pages, management pages
Merge branch 'master' of github.com:mtedeschi/OTM2 into topic/management-styling

Conflicts:
	opentreemap/treemap/css/sass/partials/_admin.scss
	opentreemap/treemap/templates/base.html
Create a map styling, pricing and progress bar
Create instance form styling
Merge pull request #557 from ahinz/topic/gate-off-more-features

Add feature gates where appropriate
Add exporter interface for celery jobs
Merge pull request #549 from ahinz/fix/346/hook-up-export-ui

Add exporter interface for celery jobs
Add in client-side geocoder. Fixes #543.

Provide both a client-side and server-side geocoder. Right now the
default is to use the client.
Merge pull request #544 from ahinz/fix/543/client-side-geocoder

Add in client-side geocoder. Fixes #543.
Session isn't always set on request
Wire up cool looking error pages. Fixes #527
Merge pull request #536 from ahinz/fix/527/add-error-handlers

Fix/527/add error handlers
Merge pull request #554 from jwalgran/topic/species-to-instance

Use single species table with instance and otm_code
Add disabled block over step 4 on create instance
Merge branch 'master' of https://github.com/azavea/OTM2 into topic/management-styling
Issues with transaction management.

Skip these tests until we can fix them later.
Allow overriding feature function with tests