Initial bookmarklet and models

closes #3 and #5 

#### features
* stub for bookmarklet interface
* bookmarklet pops up modal window 
* modal window sends post request 

#### testing
* `make resetdb` to get a database
* `make test` to run test suite
* try these urls...
* try the admin
* To pre-load your database with a bunch of links, run `python tribwire/scripts/faker.py`