Merge pull request #338 from edx-solutions/dcikatic/SOL-20-filter-changes

Dcikatic/sol 20 filter changes - merging to get eyes on - still need to confirm correct test coverage
SOL-20 Cleaning up code
Merge pull request #339 from edx-solutions/dcikatic/SOL-20-filter-changes

Dcikatic/sol 20 filter changes
SOL-87 add asset type filter unit test