Long Description usability

The Long Description text area is very important because it's the main information about a solution:

Right now it's hard to use because it's only three lines, and that doesn't encourage a good description. It should:

* Be bigger and invite a long and comprehensive description of the software
* Have rich text capabilities for formatting, like bold, italics, underline, lists and links. `longDescription` supports markdown. The GitHub textarea, simplified, could act as a good inspiration.
* Have a character count, so you know when you reached 150 characters (#441, point 8)
* Have a preview?