Added and configured Owin cookie authentication middleware
Signing in using Owin Cookie middleware
Modified Bugs page to get user information from User.Identity

Added ClaimsIdentityExtensions to encapsulate logic for retrieving
Claims from the current identity.
Modified DisplayBugs to use Identity instead of btnet.Security

Added BugPerPage claim
Row Level security using Identity instead of btnet.security.User
Added EnablePopups claim
Added CanAddBugs claim type
Added TagsPermissionLevel claim type
Added MainMenu user control