Add google_analytics collector.

[alienth]

Config looks like the following:

[[GoogleAnalytics]]
  ClientID = "blahblahblah.apps.googleusercontent.com"
  Secret = "foo"
  Token = '''
aHR0cHM6Ly93d3cueW91dHViZS5jb20vd2F0Y2g
'''

  [[GoogleAnalytics.Sites]]
    Name = "stackoverflow.com"
    Profile = "123456a"

  [[GoogleAnalytics.Sites]]
    Name = "stackoverflow-mobile"
    Profile = "2456245"
    Offset = 8

The Token is a long-lived cached oauth token. The string itself is a base64'd gob. Generating it is done by hand at the moment. I'll investigate writing a util to do this so outszzziders can use it.

Profile is a magic GA identifier. Offset is what timeslice of the real-time data we want to grab. Mobile real-time data doesn't fully converge until about 5-6 minutes, so we only want to grab the minute slice from 8 minutes ago. If Offset isn't specified or set to 0, it is set to 1 (the minimum offset which makes sense, given the nature of the data).

Note that this has been running on my VM for several months, although the code was broken in a few places. This is the cleaned up version, finally.

👓 @gbrayut @captncraig

[captncraig]

what is the type of v? magic number indexing is a bit scary. Even a comment documenting the expected layout would help.

[alienth]

v is a 'row' containing two numbers. Will add a comment.

[alienth]

@captncraig Added fixup commits.