Adding Filtering to the Companies list page

[mwfrantz]

Add the following filter fields from the screenshot attached to front end company listing page.

Regions, Industry and Classification Filters will depend on the completion of GitHub Issue #41.

Work required:

1. Add a sidebar section to the front end of the company listings page
2. Add the filter fields listed in the attached screenshot to the sidebar
3. Display companies in the company list based on filter selections