Set metadata to null on gohome event.
Merge pull request #252 from jaycee/fix-charmbrowser-home-button

Fix the charm browser's Home button search

* Set's metadata for sectionA to null on `EVT_SEARCH_GOHOME`
* Adds test to test_ui_state ensuring `metadata: null` results in navigating back to '/' from a search

QA with and without the `il` flag