Autofills vomnibar with autocompleted selections

When user moves to an autocompleted selection, its url automatically
populates the textbox. When a user pressed backspace, the selection
is set to -1 (deselected) and the list is repopulated. When the user
manually deselects autocompletions (i.e. moves up to the textbox),
the textbox is cleared
Merge pull request #7 from wgreenberg/issues/2

Autofills vomnibar with autocompleted selections