Make composer requirements more visible

Meta: [Title character requirements not very visible](http://meta.discourse.org/t/title-character-requirements-not-very-visible/5542/11)

This adds a red border on `title` and `reply` fields whenever the minimum characters requirements are not met:

![Screenshot_04_04_13_04_11](https://f.cloud.github.com/assets/362783/337308/6920b3ce-9ccd-11e2-8703-17c627a12a9e.png)