Added redirection and fixed syntax issue with sessionService
Added Header controller
show logout button with route change
Route change event added in app.js
perform authentication and add todos service factory
modify authentication logic to add authentication to each request
Merge branch 'master' into interceptor-introduction

Resolved Conflicts:
	todo-yeoman-front-end/app/scripts/app.js
	todo-yeoman-front-end/app/scripts/controllers/login_controller.js
	todo-yeoman-front-end/app/scripts/services/session_service.js