Inline Analytics

  Display of answer distribution graphics inline on the problem page
  for instructors.

  Problem types supported for graphics:
    - MultipleChoiceResponse
    - ChoiceResponse

  Problem types supported for line item display:
    - OptionResponse
    - NumericalResponse
    - StringResponse
    - FormulaResponse
    via setting

Internal review only for now.
As long as we have a CSS preprocessor, we should take advantage of it.

This block can be nested above like:
```sass
.grid-block {
    position: relative;
    float: left;
    margin: 0 25px 0 0;

    .analytics-table {
        border-collapse: separate;
        border-spacing: 1px;
    }
}
```