API Key Bandaid

Quick fix for the API limit problem - now chooses between your key and my key based on whether the current unix time is an odd or even number.  Worried to discover my very simple testing used up 8% of my key's daily quota.

Various other niceties.

I noticed that the extension doesn't show up in first pages for search term 'ruby', but it probably should.  Perhaps once we've figured out the API key business it might be an idea to change the name to "Ruby Doc Search" or similar.