Fixes Filter Tabs Margin - Fixes T361

Summary:
* adds more specificity to `[class*='field-'] {margin-bottom: 30px;}

* fixes T361

Test Plan: * check margin on tab filters and data-form-fields

Reviewers: rjmackay

Reviewed By: rjmackay

Subscribers: shadowhand

Maniphest Tasks: T361

Differential Revision: https://phabricator.ushahidi.com/D190