add coverage output to gitignore
add coverage output to gitignore

allspiritseve/aasm,hspazio/aasm,Aryk/aasm,oswaldoferreira/aasm,yui-knk/aasm,artofhuman/aasm,nickpellant/aasm,reidmorrison/aasm,intfrr/aasm,luxola/aasm,joshsoftware/aasm,awsmsrc/aasm,pskrz/aasm,ASnow/aasm,HoyaBoya/aasm,aasm/aasm,bilby91/aasm,Funfun/aasm,xieyunzi/aasm,internmatch/aasm