Fixed Firefox issues

[chuanlin2018]

This branch fixes two issues:

1. When expand/collapse filter items, white space added to the top area of landing page. This issue only happened in Firefox.
2. Search result return nothing if taxonomy tag contains comma.

Issue #1 was because of a Firefox bug related to sticky styling. The fix was to use absolute position and dynamic position.

Issue #2 was fixed by replacing filter string with object.

Tested locally in Chrome, Firefox and Safari. Not tested in docker because had some issues running docker locally even integration branch - rmm had problem accessing Mongodb.

[RayPlante]

Tested on testdata, confirmed the follow fixed under firefox:

• Grand Challenge filters work properly
• Opening up a filter does not insert extra space at the top of the page
• Research areas list wrap properly now.