Implement "give feedback" button & dialog for installed experiment detail page

[lmorchard]

Once an experiment is installed, the detail page should offer a "give feedback" button. When clicked, it should display a small survey - some radio buttons and a textfield for free-form feedback.

[lmorchard]

Some questions to resolve that impact implementation:

• Is this survey always going to be a set of radio buttons & a text field?
• Are the radio buttons the same for all experiments? Or do we want a customizable set for each experiment?
• How do we want to handle reporting on this collected data? Who's going to analyze it & how?

[lmorchard]

Per status meeting, we can just go with the questions as the are on the wireframes for now:

• Something seems broken
• Request a feature
• This is cool!
• Something else

Future expansion could include other surveying options.