Insight Toolkit : Changed version to 4.4.0 and added python wrapping

Here is a new version of the formula which enables python Wrapping.

In my last try (https://github.com/Homebrew/homebrew-science/pull/186), the problem was that the formula depended on a head-only gccxml. In this new formula, I set ITK_USE_SYSTEM_GCCXML to OFF, and use a patch to download a working version of gccxml from their github repository. I hope this is a more elegant (and accepted) solution than the previous one.

The changes done in this PR are the following :

* Changed the version to 4.4.0
* Added python support with the new python syntax
* Solved the gccxml problem through a patch for python support

Note : the only error I get from brew audit is :
> Use "#{ENV.cxx}" instead of hard-coding "g++"

Without setting g++ the build will fail, I think this a gccxml problem which will be hopefully solved soon.

Ping @scicalculator, @samueljohn and @brotoes