Allow choice of custom/default resolver in bubble

This enables an new option to show a radio button selection between
custom or default resolver in the bubble area. Only the bubble picks up
this functionality. If a custom resolver is defined, it will still
always be used for omnibox, autolink, and context menu resolving.
Use Droid Sans font
Open source software info on Options page

Hard code this in English because of reasons.
Remove save button from custom resolver fields

On the options page, update the output example and save on each change
in the custom resolver text boxes. This removes the need for a save
button.
jQuery all over

These are relatively simple (i.e. not cpu intensive) javascript
operations. Use jQuery wherever possible for code simplification and
readability.
Remove input box label from bubble

There's no need for a dedicated "DOI" label when you can write a faint
placeholder in the input box. The 3 colum text box sizing never worked
perfectly anyways.