User can search for Users

WIP: Add attributes to zombie_user
User can update zombie information
User receives full error messages upon validation failure
User can search for other users from any page

WIP: Adjust HTML
Users can view each others profiles

WIP: Update html content
WIP: Add seed data for Zombie Users
User must login to search or view home link
WIP: Added recipient_id to tweets

There is an error with SQLite that makes it so you cannot add a new
column to a table and specify null: false on it. It would normally make sense to
raise an error if we were adding null:false to a new column because
doing that in a database with entries would create rows which default to
null, but then violate the null: false. SQLite raises this exception
though regardless if there are records in the database or not. The work
around is to create a new column and then immediately change that
column. For more info see: http://stackoverflow.com/questions/3170634/how-to-solve-cannot-add-a-not-null-column-with-default-value-null-in-sqlite3
User can send and receive tweets