nice error msg for invalid chars in new card URLs

nice error msg for invalid chars in new card URLs+status

nice error msg for invalid chars in new card URLs+priority

nice error msg for invalid chars in new card URLs+tag

nice error msg for invalid chars in new card URLs+commit

nice error msg for invalid chars in new card URLs+example

If you go to http://test.dwagn.org/johnca/test and Submit, you'll see the current, not-so-nice error message.