Merge pull request #22 from SimpleReviews/media

Media
added sign in view
updated styles
added sign in route
added sign in link to the navbar
added a user model
added sign up view
added sign up view
added server-side user authentication
added an auth module to handle user authentication actions
updated views and templates and created a separate nav view
fixed sign up view conflict
resolved conflicts
Merge branch 'feature/user-accounts'
Merge pull request #25 from SimpleReviews/media

category page now includes product images
added sign out and sign up links
fix navigate url
fixed sign up form validation
Merge branch 'master' of https://github.com/SimpleReviews/core-app
added form ids