Updating astropy_helpers to v3.1
Updating astropy_helpers to v3.1

pllim/astropy,mhvk/astropy,MSeifert04/astropy,stargaser/astropy,saimn/astropy,StuartLittlefair/astropy,StuartLittlefair/astropy,astropy/astropy,bsipocz/astropy,astropy/astropy,stargaser/astropy,lpsinger/astropy,dhomeier/astropy,larrybradley/astropy,pllim/astropy,pllim/astropy,larrybradley/astropy,dhomeier/astropy,lpsinger/astropy,bsipocz/astropy,larrybradley/astropy,MSeifert04/astropy,dhomeier/astropy,astropy/astropy,StuartLittlefair/astropy,lpsinger/astropy,lpsinger/astropy,lpsinger/astropy,StuartLittlefair/astropy,mhvk/astropy,aleksandr-bakanov/astropy,astropy/astropy,MSeifert04/astropy,mhvk/astropy,mhvk/astropy,saimn/astropy,saimn/astropy,dhomeier/astropy,stargaser/astropy,aleksandr-bakanov/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,dhomeier/astropy,larrybradley/astropy,bsipocz/astropy,mhvk/astropy,bsipocz/astropy,aleksandr-bakanov/astropy,pllim/astropy,MSeifert04/astropy,pllim/astropy,astropy/astropy,stargaser/astropy,larrybradley/astropy,saimn/astropy,saimn/astropy