Validation error messages large on ecommerce page

# Resolves https://github.com/optimizely/marketing-website/issues/516

## Formerly:
![screen shot 2014-10-15 at 11 40 57 am](https://cloud.githubusercontent.com/assets/2864449/4653748/6c002a92-54b0-11e4-87a6-9aa02d7096b6.png)

## Now:
![screen shot 2014-10-15 at 11 40 10 am](https://cloud.githubusercontent.com/assets/2864449/4653755/77f1522c-54b0-11e4-8552-555e53b527e8.png)