pygal added to Data Visualization

http://pygal.org/
Add PEW of python environment management tool
add module freezegun
add module HTTPretty
Add libsass-python
Merge pull request #105 from ldong/master

Add PEW of python environment management tool
Merge pull request #106 from grigouze/module_freezegun

add module freezegun
Added Vex in Environment Management tools
Update README.md
Add Toolz and CyToolz
Move Toolz and CyToolz to the "Functional Programming" section
Add django-viewlet
Merge pull request #111 from shvechikov/master

Add Toolz and CyToolz
Add django-formapi
added api resource
Fix spelling
great httplib2 added to HTTP section
Merge pull request #108 from dahlia/master

Add libsass-python
Merge pull request #109 from mgill25/master

Added Vex in Environment Management tools
Merge pull request #110 from DTVD/master

Add Rainbow Stream (Command line Tools)