Merge tag '0.1' into develop

Version 0.1

Basic flickr api integration
Merge tag '0.1.1' into develop

Move sqlite3 gem to development and test groups
Merge tag '0.1.2' into develop

Require net/http for flickr_sss service. Heroku doesn't autoload this one.
Add url for example app to README.md
Add dotenv gem instructions to README.md
Improve README.md
Specify ruby version in Gemfile
DRY specs
Improve API a little
Bump version number to 0.2.0
Update Readme
Merge branch 'release/0.2.0'
Bump version number to 0.2.1
Re-add pg gem - required by heroku's default buildpack
Merge branch 'hotfix/0.2.1'