Added rake task to import new crops from CSV
Load multiple crop CSV files from seeds.rb

We factored out a Crop.create_from_csv method to avoid duplicated code.

Note: naming convention with db/seeds/crop*.csv is to use a 2-digit
number for ordering.  00 and 10 chosen (with a gap in between) because I
learned to program in BASIC and it seemed like a good idea just in case.
Added some comments/docs to Crop.create_from_csv
Turn on better_errors in development.
Rename Crop.system_name to Crop.name
Added rails_12factor gem to suppress heroku messages
Merge pull request #331 from Skud/rails_12factor

Added rails_12factor gem to suppress heroku messages
Added posts and comments RSS links
Merge pull request #332 from Skud/rss-links

Added posts and comments RSS links
Merge pull request #329 from pozorvlak/better_errors

Turn on better_errors in development.
Merge pull request #328 from Skud/crop-csv-upload

Crop csv upload
Merge branch 'system_name_to_name' of https://github.com/pozorvlak/growstuff into pozorvlak-system_name_to_name

Conflicts:
	db/seeds.rb
Fixing up confused crop names from two recent pull requests
Removed intentional errors accidentally left in when testing better_errors
Added various fields to garden

- active (default: true)
- location, latitude and longitude (because when you move house, you
    don't take your garden with you)
- area and area units (square feet or metres)
Added new fields to garden form
Added new garden fields to gardens/show
Added active/inactive scopes
Added new fields to gardens index
Only list active gardens in planting form