Add virtualenv dependency
Add virtualenv dependency

Closes #21

imcom/pyleus,dapuck/pyleus,patricklucas/pyleus,Yelp/pyleus,patricklucas/pyleus,ecanzonieri/pyleus,jirafe/pyleus,stallman-cui/pyleus,jirafe/pyleus,poros/pyleus,mzbyszynski/pyleus,mzbyszynski/pyleus,dapuck/pyleus,Yelp/pyleus,stallman-cui/pyleus,imcom/pyleus,poros/pyleus,imcom/pyleus,ecanzonieri/pyleus