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Begin creating service to handle user auth
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Change user session system from service to provider
Use a provider instead of $rootScope to store user session state

It is best practice to avoid using $rootScope (much like avoiding global scope)
Remove trailing space
Add script tag for UserProvider
Use provider instead of  to store user session state
Add necessary  method to provider
Refactor to correct design pattern for ng providers
Fix login conditional expression
Change submit button disabling to use ng-disabled