rename source and SWIG files to follow UpperCamelCase convention 

This is the PR for #819 , depends on numenta/nupic.core#76 and #834 .

Not ready for merge yet, but for inspection.

Replaces #829 due to multiple failed attempts to trigger Travis build.

Things left to be done:

* it's still undecided whether to rename to UpperCamelCase and whether to rename .i files on hackers' ML 
* This PR assumes the conclusion would be:
   - rename to UpperCamelCase
   - rename .i files too
   - Do NOT rename `BufferIO` to `BufferIo`, both for class name and file name, use the following convention instead:
     +  [When using acronyms, use Pascal case or camel case for acronyms more than two characters long. For example, use HtmlButton or htmlButton. However, you should capitalize acronyms that consist of only two characters, such as System.IO instead of System.Io. ](http://msdn.microsoft.com/en-us/library/141e06ef%28v=vs.71%29.aspx)
     +  So, `IO` and `Html` and `Csv`
* numenta/nupic.core#76 must be merged before this, and `.nupic_modules` must be updated