Escape views with builtin document syntax

It's a fix for https://github.com/TMXCredit/pg_power/issues/49

## Changes
* Use builtin document instead of double quote for view defenitions.

## RSpec
```
Finished in 0.9812 seconds
156 examples, 0 failures, 3 pending
Coverage report generated for RSpec to /home/blake/dev/work/tmx/pg_power/coverage. 741 / 763 LOC (97.12%) covered.

Coverage: 97.11664482306684% is over the threshold: 97.116%.
```

## Doc
Not affected