Refactored scroll spy handling.
Refactored scroll spy handling.

MartyIX/angular-scroll,Ibanheiz/angular-scroll,Nitsorn/angular-scroll,suns1191/angular-scroll,oblador/angular-scroll,pkaminski/angular-scroll,Drooids/angular-scroll,MartyIX/angular-scroll,Ibanheiz/angular-scroll,homerjam/angular-scroll,eaze/angular-scroll,anthony-legible/angular-scroll,homerjam/angular-scroll,suns1191/angular-scroll,Nitsorn/angular-scroll,eaze/angular-scroll,pkaminski/angular-scroll,Drooids/angular-scroll,blak3mill3r/angular-scroll,durated/angular-scroll,fauverism/angular-scroll,fauverism/angular-scroll,oblador/angular-scroll,anthony-legible/angular-scroll,1wheel/angular-scroll