Add users to schema

To prepare for authentication feature.
Some shortcuts taken to bypass the need for a task to have a valid
user_id.
Update seeds file to include a sample user
Add User entity and UserRepository
Add session controller
Adds LoginCtrl controller and specs

Added sinonjs bower package so that we can stub and mock the
AuthService dependency (we havn't written this yet).
Needed to add 'sinon' to the list of included files and to .jshintrc
(so that undeclared variable is ignored).
Finally need to stub the promise that we expect the service to return.
Adds session controller to server side
Add some tests for the LoginCtrl

Stubbing out the authentication service was not as obvious as expected.
First had to use sinon to stub out the service's login method and return
a promise.  When using Angular's own $q promises, to resolve the promise
need to call `$rootScope.apply()` as well as `resolve()` on the deferred
object itself.

Its all a bit over-engineered for what it really is but maybe its a
useful exercise in isolating components.
Fill in some missing specs for LoginCtrl
Add some specs for the AuthenticationService

This is just a simple wrapper around $http. `login` just transforms the
result so that it returns the user rather than the HTTP response.
Again probably overengineered for what it is.
Implement a very simple view for the Login Controller
Capture the logged in state in the AuthenticationService
Redirect to /login if not logged in
Login/logout function on login controller/view
Merge branch 'master' into oauth
Adds database session store
Fixes rendering error in Sessions::Delete action

In order to skip view rendering we need to set the response body to a
string not a hash!
Add navigation bar controller to handle visibility of links
Move logout function to the nav bar controller

Logout button should be available on the main menu and should
automatically navigate us to the login screen.
Removes redundant logout function from the login controller
Merge pull request #1 from stevehook/auth

Basic authentication infrastructure (insecure)