Add a skeleton for the MIT "county performance" page
A initial static version of the MIT county performance page

This is a squash of 5 commits by Zarino with the following commit
messages:

  * first iteration of coding up the illustrator mockup
  * facebook and twitter icons on country-performance buttons
  * red table column
  * fix country/county typo
  * fix mobile h2 style overrides on country-performance page
fix comment form button width on small screens
make county-performance table scale down nicely on narrow screens
Suppress the survey banner on the MIT page
MIT: Add a Django Form for the "petition" form
MIT: Add a Django Form for the "comments for the senate" form
MIT: Present "Opportunity", "Threat" or neither depending on variant
MIT: Randomly order the Facebook and Twitter share buttons
MIT: Shuffle the senate comments, petition sign up and share buttons
MIT: Handle submissions to either form on the county performance page

Paul has said that we only need to create entries using the existing
feedback mechanism; so this just adds submissions for petition
signatures or comments for the senate to the feedback for these
pages respectively:

  /county-performance/petition
  /county-performance/senate

... marked as non-actionable.

There is some juggling of class-based views required to work with
two forms on a single page, and so that if the form don't pass
validation, the user is redirected to a reduced version of the
page with just the form they were trying to fill.

Note that this doesn't confirm that the supplied email address
actually works (as with the existing feedback mechanism) - for a
serious petitions system one would want to make sure the email
address entered is usable.
MIT: Correct indentation according to our policy for HTML templates

(Keeping this indentation change in a separate commit from the
previous one makes the earlier commit clearer without having to
add -w.)
MIT: Present all validation errors together, not field-by-field
MIT: Use the HTML5 'required' attribute in input elements
add styling for county performance form validation errors
Add a basic 'experiments' app for recording the results of experiments

The motivation for this is that we need to record more information
than can be easily recorded in Google Analytics alone for the MIT
county performance page experiment.  For example, they want to be able
to cross-reference particular survey responses with any actions on the
page earlier, so we need to record some unique ID for them.

However, this might well be useful as a framework for other experiemnts
in the future in any case.
Add a JSON extra_data field to each experiment event

It would be nice to migrate to using django-hstore for this in the
future, but that would mean making sure that the Postgres hstore
extension is loaded, which involves some thinking + changes that I don't
have time for at the moment.  So, in the interim, just make sure that
people don't use this field for non-JSON data via the admin interface.
MIT: record passed-in parameters and actions taken

We will be supplied the following parameters from the Facebook
advertisements:

  g: Gender, either 'm' or 'f'
  agroup: Age group, either 'u' (under) or 'o' (over) some threshold

There will also be a 'variant' parameter indicating which variant of
the page is being used.  Finally, we create a "user key", which is really
just a random number associated with the original page view).

All of these parameters need to be recorded as events in the experiments
app whenever the user submits one fo the forms on that page.  Some of
this data (user_key, variant) first into columns in the
experiments_events table anyway, while the rest (g, agroup) are recorded
as JSON in its extra_data column.

As well as introducing those changes, this commit does some refactoring
to remove repetition in the form_valid method.
MIT: record clicks on Facebook and Twitter buttons

These need to be recorded both in Google Analytics (as an
event, using hitCallback, and in our experiments_events
table.
MIT: Make requested changes to the county performance page copy

These were requested in issue #1307