Add Guestbook Model And Implement User Tests

This commit adds a guestbook model and implements
tests for the user model. These are being done at
once instead of separately because I was sloppy with
the users model and wrote no tests.
Add Root URL With Messages Displayed, Add New Partial

This commit makes the 'show' method for the guestbook
messages be the home URL of the app. It also adds a
partial so that a new message can be posted from the home
URL, and adds tests to validate the guestbook message data.
Add Working Message Partial

This commit allows the user to add guestbook messages to the front page
of the guestbook app. The controller has been updated to correctly
parse the parameters hash and commit the changes to the database.
Guestbook Message Validation And Dynamic Location

This commit adds validation to save a guestbook message and changes
the location field so that it is dynamic, based on the current user,
rather than set to a static value in a hidden field.
Add Bootstrap To Application

This commit adds out-of-the-box Bootstrap to the application.
Final Edits To Guestbook Model

These edits allow the guestbook model to restrict access to the post
form based on whether or not the user is logged in.
Merge pull request #4 from cpalmer8/guestbook_model

Guestbook model