[Form & Profiler] Improve error displaying

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | ~
| License       | MIT
| Doc PR        | ~

I made this PR, because on huge form, I can't find which field has error(s)

![The Form Profiler](https://f.cloud.github.com/assets/166890/1993693/7c5698a6-84de-11e3-9240-1d7181e37385.png)