initial checkin
check in first migrations
flesh out model relations
fix up shortened_url relations
fixes fixes fixes
reorder validations and associations
add a lot of comments on special has_many options
has_many :through never needs to specify class_name
ShortenedUrl: add clicks methods
Visit: add register_visit factory method
ShortenedUrl: enforce uniqueness of urls
ShortenedUrl: write class method to generate
add migrations to create tag tables
add tagging models
add tagging associations
Merge branch 'add_tags'
Tag: track most popular links within a tag
Tag: add convenience for affixing tags
Tag: forgot to order by clicks