[Feature request] Update safari's default search engine chrome

[AndrewSB]

Currently, safari shows search <default safari search engine>, it would be an awesome cosmetic change if it instead showed my default search engine in omnikey. My default isn't google, so it degrades the awesomeness of omnikey by just a little bit

Low-pri, of course. Bugs are more important, like the state not updating until restart in #21