Add support for Python v2 compatibility

[cmlccie]

For API reference libraries like this, to aid in adoption, it is very helpful if the package can be written to provide compatibility for both Python v2 and v3.

Having just gone through this process (taking a v2 package that I authored, and adding support for v3) sometimes the needed changes are trivial and sometimes they are easy. Based only on a quick look at the package's code and dependencies, this may not be to intensive of an update if leveraging some of the tools and packages that have been created to assist with efforts like these.

conversion assistance script... pasteurize: Py3 to Py2/3

Packages:

• future
• six