Add sessions login partial

Remove previous user login/logout/signup partials
dd partial views

Separate favorites menu and individual artists in favorites menu
Partials can now be included/appended in different scenarios:
-user login
-existing user

Add css styles for new partials - login link, search box when fav menu exists
Add user login/logout functionality

-ajax get for user login partial
-ajax post for user login submit
-session create render favorites menu partial
-session new render login form partial