Downloads git sub dir

##Usage

python get_git_sub_dir.py path/to/sub/dir <RECURSIVE>

is a boolen True or False. Default is True.

##Example

Lets download the docs from twitter bootstrap https://github.com/twbs/bootstrap/tree/master/docs

python get_git_sub_dir.py twbs/bootstrap/docs

If we don't want it to be recursive

python get_git_sub_dir.py twbs/bootstrap/docs False