Update error pages to confirm to design pattern

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Closes #140
5 jobs for 68-signup-help in 2 minutes and 51 seconds
Status Job ID Name Coverage
  Test
passed #2724
Go-py2.7

00:01:32

passed #2725
Go-py3.4

00:01:34

passed #2726
Go-py3.5

00:01:37

passed #2727
Go-py3.6

00:01:35

 
  Lint
passed #2728
Go-flake8

00:01:13