Issue title: Get rid of references to nctoolbox google code site
 Issue body: We still have references to the google code site, which users find confusing.

Let's move any remaining documentation to github

What still needs to be done?

 Comments: 
 Comment 0: I think we still need to finish moving documentation from the google site to github. I don't suppose anyone on your end is working on that?

 Comment 1: I could do some of this if I knew what to move.  @acrosby do you remember what is still left to be done?
(I can just poke around and try to figure it out, but if you remember what you have already done and what is left to do, we could itemize it in this issue).

 Comment 2: bump.

It looks like none of the http://code.google.com/p/nctoolbox/wiki/Documentation is ported over here.  The tutorial and reference documentation is helpful.

Ack.  There seems to be help on the http://nctoolbox.github.io/nctoolbox/ but where is the code or whatever for it?  It seems to show a working demos/geodemo4 somehow: http://nctoolbox.github.io/nctoolbox/demos/geodemo_4.html 

Edit: the code for some of the help stuff is on the https://github.com/nctoolbox/nctoolbox/tree/gh-pages while there is other help on the https://github.com/nctoolbox/nctoolbox/wiki link.

 Comment 3: I think the only remaining references to googlecode are to:
- html5shiv.googlecode.com/svn/trunk/html5.js in some headers
- some help files where it refers to the old site explicitly.
- Issue #41 or GC Issue# 27

 Comment 4: html5shiv is a reference to an external javascript library. Please do not change the reference. 

 Comment 5: It looked like it was important, and probably not what this ticket was about.

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