Add specific check for bad mail content

Right now, the code means you can get emails that say:

```
See you next next week!
```

or

```
See you next tomorrow!
```
Fix for content

Now we say `See you tomorrow!` OR `See you next week!` :+1:
Merge pull request #803 from petems/fix_email_content

Fix issue accidentally introduced in #785
fixing seed file to make sure it runs again
Merge pull request #805 from indykid/seed_fix

fixing seed file to make sure it runs again
#799 changing error message around Coderwall linking
Merge pull request #806 from startmyquest/master

Change remove button text for twitter
assisning correct class to flash alert
Merge pull request #807 from indykid/github_linking

GitHub linking