Add note about Travis circular dep problem
Add note about Travis circular dep problem

stevage/when,frank-weindel/when,tkirda/when,SourcePointUSA/when,caporta/when,caporta/when,icodeforlove/whenplus,DJDNS/when.js,petkaantonov/when,mlennon3/when,anthonyvia/when,stevage/when,SourcePointUSA/when,mlennon3/when,ning-github/when,frank-weindel/when,anthonyvia/when,tkirda/when,ning-github/when