Improve usage statistics with module/theme filters and version specific data.

Problem/Motivation

In order to better understand the Drupal contrib ecosystem it would be helpful for the Project usage overview (https://drupal.org/project/usage/) page to have additional functionality. Specifically it would be helpful to filter on whether something is a module or theme and also to look at specific Drupal version details rather than just totals.

Currently the only way to get version specific data is to look at each projects usage data. While this information is helpful on a per module or theme basis a more global understanding of contrib could help the community better assess the needs of those potentially migrating from D6 to D8, when it becomes available, as well as to see variations in module/theme rankings by Drupal version.

Proposed resolution

Add filters to this page to allow for the user the ability to only show modules or themes, as well as look at specific Drupal version data, without having to dig through each projects usage data.

Remaining tasks

Get access to a development site or environment with drupal.org data.
Update project/usage/includes/pages.inc with the new functionality.

User interface changes

The addition of filters on the Project usage overview (https://drupal.org/project/usage/) page would be below the help text but above the table. These would need to be implement standard conventions of the drupal.org design.

API changes

None