feat: add strings.Contains support
feat: add strings.Contains support

closes #270

Ropes/confd,okushchenko/confd,crandles/confd,danesparza/confd,agilemobiledev/confd,glerchundi/renderizr,gautamk/confd,axingblog/confd,zytek/confd,elbidigital/confd,philipsoutham/confd,elsonrodriguez/confd,tomdee/confd,tomdee/confd,Lineberty/confd,aledbf/confd,crunchywelch/confd,danesparza/confd,crandles/confd,blippar/confd,Fitbit/confd,monder/confd,axingblog/confd,Fitbit/confd,alexnauda/confd,israelchen/confd,nevermosby/confd,elbidigital/confd,kelseyhightower/confd,zytek/confd,shencan/confd,karthequian/confd,Flipkart/confd,crunchywelch/confd,elsonrodriguez/confd,shencan/confd,say5/confd,jnummelin/confd,cvrabie/confd,kgrvamsi/confd,agilemobiledev/confd,glerchundi/confd,israelchen/confd,karthequian/confd,okushchenko/confd,cvrabie/confd,rancher/confd,nevermosby/confd,aledbf/confd,glerchundi/confd,openedbox/confd,PrFalken/confd,mboersma/confd,Ropes/confd,philipsoutham/confd,cloudnautique/confd,glerchundi/renderizr,chendh521/confd,jnummelin/confd,alexnauda/confd,blippar/confd,beni55/confd,linearregression/confd,chendh521/confd,say5/confd,rancher/confd,kgrvamsi/confd,bacongobbler/confd,mboersma/confd,Flipkart/confd,PrFalken/confd,RichardKnop/confd,monder/confd,beni55/confd,Flipkart/confd,RichardKnop/confd,kelseyhightower/confd,cloudnautique/confd,openedbox/confd,bacongobbler/confd,gautamk/confd,Lineberty/confd,linearregression/confd