Remove call to external commands and various fixes on Windows part 2
Remove call to external commands and various fixes on Windows part 2

Summary:
In rebasing the original PR
(https://github.com/facebook/flow/pull/1182) I lost a few changes. This diff
picks them back up

Reviewed By: mroch

Differential Revision: D2792581

fb-gh-sync-id: d0e0b073c8624a7a7ce8ef1f5dcd274a2f971bb2

d14b3l/flow,gabelevi/flow,d14b3l/flow,gabro/flow,facebook/flow,d14b3l/flow,popham/flow,popham/flow,claudiopro/flow,AgentME/flow,ylu1317/flow,popham/flow,AprilArcus/flow,MichaelDeBoey/flow,ylu1317/flow,gabelevi/flow,TiddoLangerak/flow,nmote/flow,AprilArcus/flow,graue/flow,fletcherw/flow,jamesgpearce/flow,jgrund/flow,AprilArcus/flow,claudiopro/flow,claudiopro/flow,jamesgpearce/flow,JonathanUsername/flow,mroch/flow,graue/flow,gabro/flow,ForbesLindesay/flow,gabelevi/flow,fletcherw/flow,ForbesLindesay/flow,TiddoLangerak/flow,ylu1317/flow,cesarandreu/flow,jdelStrother/flow,samwgoldman/flow,mroch/flow,jeffmo/flow,nmote/flow,samwgoldman/flow,gabelevi/flow,claudiopro/flow,nmote/flow,JonathanUsername/flow,nmote/flow,jgrund/flow,shiftcars/flow,facebook/flow,samwgoldman/flow,ylu1317/flow,jdelStrother/flow,mroch/flow,JonathanUsername/flow,jgrund/flow,graue/flow,fletcherw/flow,samwgoldman/flow,MichaelDeBoey/flow,cesarandreu/flow,shiftcars/flow,ylu1317/flow,chenglou/flow,shiftcars/flow,AprilArcus/flow,d14b3l/flow,nmote/flow,gabro/flow,cesarandreu/flow,fletcherw/flow,jamesgpearce/flow,samwgoldman/flow,jeffmo/flow,ForbesLindesay/flow,d14b3l/flow,jamesgpearce/flow,nmote/flow,jdelStrother/flow,jamesgpearce/flow,claudiopro/flow,mroch/flow,AprilArcus/flow,chenglou/flow,gabelevi/flow,mroch/flow,mroch/flow,jgrund/flow,facebook/flow,facebook/flow,chenglou/flow,cesarandreu/flow,JonathanUsername/flow,popham/flow,AprilArcus/flow,gabro/flow,popham/flow,graue/flow,ForbesLindesay/flow,chenglou/flow,MichaelDeBoey/flow,facebook/flow,MichaelDeBoey/flow,chenglou/flow,samwgoldman/flow,popham/flow,AgentME/flow,jeffmo/flow,ForbesLindesay/flow,JonathanUsername/flow,jdelStrother/flow,nmote/flow,facebook/flow,jgrund/flow,TiddoLangerak/flow,JonathanUsername/flow,ForbesLindesay/flow,MichaelDeBoey/flow,popham/flow,shiftcars/flow,facebook/flow,AgentME/flow,jeffmo/flow,fletcherw/flow,graue/flow,jamesgpearce/flow,fletcherw/flow,jdelStrother/flow,gabro/flow,graue/flow,jeffmo/flow,chenglou/flow,gabro/flow,jeffmo/flow,jamesgpearce/flow,AgentME/flow,AgentME/flow,shiftcars/flow,TiddoLangerak/flow,gabelevi/flow,mroch/flow,gabelevi/flow,jdelStrother/flow,TiddoLangerak/flow,JonathanUsername/flow,d14b3l/flow,shiftcars/flow,jgrund/flow,samwgoldman/flow