change entity name
database table name changed
added UserId column to Workshifts table **it seems that FluentMigrator does not support yet**
added Opened property and CloseTill method to workshift entity
implemented WorkshiftsService and WorkshiftsRepository
Login/Logout functionality acomplished

Added Logout, TillAmount froms

Users can now login and open workshift till to start sales process (with a started amount if he/she wants), also users can close his/her opened till and end with his/her workshift
When a user closes the application and doesnt close his/her till, till remains opened until he/she closes it at next time that he/she execute the system