Fix failing tests by providing controller object

In test the Gon JSON rendering fails because in TestRequest there is no
controller instance available. By explicitly passing the controller
object in the code, this disappears, fixing the tests.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add route to deliver quality distribution as JSON

Due to a small time gap the database needs to query the quality
distribution I am going to use an AJAX request to retrieve the
data. Hence, I have added a new route.

I have also extended the indexes. When using a compound index
and the whole query only accesses the index then the query is
executed a lot faster. At least normally, I am getting quite
contradictory explanations from the MongoDB shell and Mongoid,
but for now it should suffice.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Load quality distribution data dynamically

Since the quality distribution takes too much space in gon I have
delegated the whole data retrieval to an AJAX request.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add spinner to bridge the distribution retrieval

A loading spinner is displayed until the requested quality distribution
data has been received to display.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>