Fix for intermittent failing previews tests

Fixes:
```
Preview processor Preview generation verify reprocessing a preview processes the revision preview:
     Uncaught TypeError: Cannot read property 'alias' of undefined
```

This bug was caused because the previous test submitted `c:camtest:someContent` and `c:camtest:someRevision`
which passed validation but made the PP trip up.
Touching README.md to trigger a travis build
Merge pull request #788 from simong/previews-tests

Fix for intermittent failing previews tests