Use /usr/bin/env python
Use /usr/bin/env python

Summary: Use python from env, instead of the distro installed one in /usr/bin

Test Plan:
Ran arc anoid on a system that only had python in /usr/bin, still
works. Ran arc anoid on a system that had a python in /usr/local/bin before
/usr/bin.  Still works as well

Reviewers: epriestley, alanh

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3451

dguo-coursera/arcanist,jra3/arcanist,uber/arcanist,julkiewicz/arcanist,Symplicity/arcanist,kevinseelbach/arcanist,fivestars/arcanist,wxstars/arcanist,coursera/arcanist,chundongwang/arcanist,uber/arcanist,hach-que/arcanist,haskell-infra/arcanist,eSpark/arcanist,zhihu/arcanist,r4nt/arcanist,kevinseelbach/arcanist,wharris/arcanist,aik099/arcanist,fivestars/arcanist,chundongwang/arcanist,wikimedia/phabricator-arcanist,codelabs-ch/arcanist,coursera/arcanist,KieranHayes/arcanist,aik099/arcanist,wharris/arcanist,wharris/arcanist,Khan/arcanist,KieranHayes/arcanist,wharris/arcanist,fivestars/arcanist,r4nt/arcanist,Khan/arcanist,dguo-coursera/arcanist,Khan/arcanist,dguo-coursera/arcanist,alexmv/arcanist,PageUpPeopleOrg/arcanist-patches,wxstars/arcanist,codelabs-ch/arcanist,hach-que/arcanist,folsom-labs/arcanist,wikimedia/phabricator-arcanist,hach-que/arcanist,haskell-infra/arcanist,Khan/arcanist,alexmv/arcanist,jra3/arcanist,folsom-labs/arcanist,coursera/arcanist,calblueprint/arcanist,zhihu/arcanist,Symplicity/arcanist,memsql/arcanist,phacility/arcanist,sneakpeeq/arcanist,calblueprint/arcanist,hach-que/arcanist,fivestars/arcanist,calblueprint/arcanist,jra3/arcanist,r4nt/arcanist,eSpark/arcanist,aik099/arcanist,julkiewicz/arcanist,memsql/arcanist,phacility/arcanist,zhihu/arcanist,coursera/arcanist,eSpark/arcanist,sneakpeeq/arcanist,r4nt/arcanist,KieranHayes/arcanist,PageUpPeopleOrg/arcanist-patches,dguo-coursera/arcanist,memsql/arcanist,kevinseelbach/arcanist,phacility/arcanist,phacility/arcanist,chundongwang/arcanist,haskell-infra/arcanist,KieranHayes/arcanist,sneakpeeq/arcanist,uber/arcanist,eSpark/arcanist,memsql/arcanist,alexmv/arcanist,folsom-labs/arcanist,codelabs-ch/arcanist,PageUpPeopleOrg/arcanist-patches,haskell-infra/arcanist,alexmv/arcanist,codelabs-ch/arcanist,kevinseelbach/arcanist,aik099/arcanist,PageUpPeopleOrg/arcanist-patches,sneakpeeq/arcanist,folsom-labs/arcanist,phacility/arcanist,Symplicity/arcanist,codelabs-ch/arcanist,wxstars/arcanist,uber/arcanist,julkiewicz/arcanist,wikimedia/phabricator-arcanist,wxstars/arcanist,zhihu/arcanist,wikimedia/phabricator-arcanist,chundongwang/arcanist,Symplicity/arcanist,jra3/arcanist,julkiewicz/arcanist,calblueprint/arcanist