Add "Invalid TLD" error message

Currently, when creating a domain, if the TLD doesn't match,
the error message returned is "invalid domain name". An error
of "Invalid TLD" would be clearer to the user.

Change-Id: Iaffbbe2d79a65dccead0f6e82a0b97865aa646a2
Fixes: bug #1208874
Merge "Add "Invalid TLD" error message"