Fixes deprecation warnings with formtastic

This fixes the depcrecation warnings with formtastic. I also updated
ActiveAdmin to v0.5.1. We will still need to remove
ActiveAdmin::Dashboard which is also depcrecated as of v0.6.0 (see #11
& #12).
Removes .env file from repo and creates sample file

I think this falls in the category of app instance or user specific info
and hence it should not be included in the repo.
[Fixes #10] Move factories to spec/factories
Adds db:prepare rake task

Adds a db:prepare rake task to help speed up the dev env setup. This
task will create the database and user based on the information in the
database.yml.
adding dev doc (clean)
docs specify rvm instead of rbenv
added spring for rspec (clean)
Indexing the correct fields, as content_md isn't used anymore
Merge pull request #25 from adelevie/feature/spring_clean

added spring for rspec (clean)
Merge pull request #22 from 18F/feature/fix_formtastic_deprecation_warnings

Fixes deprecation warnings with formtastic
Merge pull request #20 from 18F/feature/remove_env_from_repo

Removes .env file from repo and creates sample file
Merge pull request #24 from adelevie/feature/dev_setup_docs_clean

adding dev doc (clean)
Merge pull request #21 from 18F/feature/move_factories_to_spec/factories

[Fixes #10] Move factories to spec/factories
Merge pull request #15 from 18F/feature/add_db_prepare_task

Adds db:prepare rake task
Query the correct content fields
Fixes issue with category and guides

Guides were not displaying because of a missing ‘,’ in the meta tag
information in the guides view. Added a helper to generate the meta_tag
options

Also fixed and issue where the categories were not linking to the
correct article urls.

Gave the category factory a more proper title using Faker.