Fix tag order
Fix tag order

fixes #4151
- Properly re-add pre-existing tags to beginning of array

JohnONolan/Ghost-Admin,dbalders/Ghost-Admin,kevinansfield/Ghost-Admin,acburdine/Ghost-Admin,JohnONolan/Ghost-Admin,dbalders/Ghost-Admin,TryGhost/Ghost-Admin,acburdine/Ghost-Admin,TryGhost/Ghost-Admin,airycanon/Ghost-Admin,kevinansfield/Ghost-Admin,airycanon/Ghost-Admin