add python-snappy to server builds

In order to fix MB-10597, we need to

[X] clone https://github.com/andrix/python-snappy under github.com/couchbase
[ ] add python-snappy to Windows builds
[X] check to see if python 2.4 is installed on all build machines
[X] verify that adding python 2.4 does not modify build environment for 2.x server builds
[X] add python 2.4 to any build machines it's missing from