Create routes to direct to new session

*Change root path to "sessions#new"
*add get path for "/sign_in" and for "/sign_up"
Create migration to add Admin column to Users table
Remove monbahn sign in constraints

*Remove as it is not in use at this time
Merge branch 'abs-sign-in'

* abs-sign-in:
  Remove monbahn sign in constraints
  Create migration to add Admin column to Users table
  Create routes to direct to new session