added tests for Casper#exists
added tests for Casper#exists

muntasir2000/casperjs,mcwonka/casperjs,artillery/casperjs,linkedin/casperjs,hexid/casperjs,vietch2612/casperjs,hlr1983/casperjs,mcwonka/casperjs,dj31416/casperjs,JZL/casperjs,PeterWangPo/casperjs,RobertoMalatesta/casperjs,vietch2612/casperjs,istr/casperjs,jamesanthonyferguson/casperjs,RobertoMalatesta/casperjs,pbrazdil/casperjs,davidwhthomas/casperjs,flyHe/casperjs,muntasir2000/casperjs,kyroskoh/casperjs,HienLeThi/Casperjs_Demo,dj31416/casperjs,sircelsiussexy/casperjs,linkedin/casperjs,vietch2612/casperjs,cryptoquick/casperjs,linkedin/casperjs,sircelsiussexy/casperjs,davidwhthomas/casperjs,JZL/casperjs,hexid/casperjs,sircelsiussexy/casperjs,casperjs/casperjs,dj31416/casperjs,vladikoff/casperjs,mcwonka/casperjs,n1k0/casperjs,PeterWangPo/casperjs,jamesanthonyferguson/casperjs,davidwhthomas/casperjs,Andrey-Pavlov/casperjs,joshuafcole/casperjs,alexbiehl/casperjs,pbrazdil/casperjs,ravindrasingh22/casperjs,ravindrasingh22/casperjs,muntasir2000/casperjs,singhdev/casperjs,jefleponot/casperjs,jjyycchh/casperjs,flyHe/casperjs,kyroskoh/casperjs,jjyycchh/casperjs,jefleponot/casperjs,ravindrasingh22/casperjs,alexbiehl/casperjs,JZL/casperjs,hlr1983/casperjs,jjyycchh/casperjs,hlr1983/casperjs,davidwhthomas/casperjs,n1k0/casperjs,hudl/casperjs,vladikoff/casperjs,Andrey-Pavlov/casperjs,casperjs/casperjs,joshuafcole/casperjs,mickaelandrieu/casperjs,singhdev/casperjs,sircelsiussexy/casperjs,alexbiehl/casperjs,mcwonka/casperjs,hudl/casperjs,singhdev/casperjs,pbrazdil/casperjs,singhdev/casperjs,jefleponot/casperjs,alexbiehl/casperjs,linkedin/casperjs,HienLeThi/Casperjs_Demo,pcarrier-packaging/deb-casperjs,RobertoMalatesta/casperjs,n1k0/casperjs,hexid/casperjs,jamesanthonyferguson/casperjs,pcarrier-packaging/deb-casperjs,davidwhthomas/casperjs,Andrey-Pavlov/casperjs,pcarrier-packaging/deb-casperjs,jefleponot/casperjs,jamesanthonyferguson/casperjs,mickaelandrieu/casperjs,flyHe/casperjs,RobertoMalatesta/casperjs,JZL/casperjs,muntasir2000/casperjs,mcwonka/casperjs,n1k0/casperjs,kyroskoh/casperjs,hudl/casperjs,hlr1983/casperjs,mickaelandrieu/casperjs,JZL/casperjs,vietch2612/casperjs,n1k0/casperjs,jjyycchh/casperjs,casperjs/casperjs,casperjs/casperjs,cryptoquick/casperjs,hudl/casperjs,hlr1983/casperjs,alexbiehl/casperjs,flyHe/casperjs,hlr1983/casperjs,cryptoquick/casperjs,pbrazdil/casperjs,hexid/casperjs,artillery/casperjs,joshuafcole/casperjs,ravindrasingh22/casperjs,istr/casperjs,kyroskoh/casperjs,sircelsiussexy/casperjs,sircelsiussexy/casperjs,casperjs/casperjs,PeterWangPo/casperjs,linkedin/casperjs,soundyogi/casperjs,soundyogi/casperjs,HienLeThi/Casperjs_Demo,HienLeThi/Casperjs_Demo,Andrey-Pavlov/casperjs,jefleponot/casperjs,vladikoff/casperjs,HienLeThi/Casperjs_Demo,kyroskoh/casperjs,JZL/casperjs,ravindrasingh22/casperjs,artillery/casperjs,mcwonka/casperjs,pbrazdil/casperjs,flyHe/casperjs,hexid/casperjs,linkedin/casperjs,pbrazdil/casperjs,istr/casperjs,soundyogi/casperjs,n1k0/casperjs,joshuafcole/casperjs,artillery/casperjs,flyHe/casperjs,cryptoquick/casperjs,jjyycchh/casperjs,istr/casperjs,dj31416/casperjs,artillery/casperjs,hudl/casperjs,artillery/casperjs,ravindrasingh22/casperjs,muntasir2000/casperjs,hexid/casperjs,kyroskoh/casperjs,HienLeThi/Casperjs_Demo,PeterWangPo/casperjs,cryptoquick/casperjs,casperjs/casperjs,mickaelandrieu/casperjs,joshuafcole/casperjs,vietch2612/casperjs,mickaelandrieu/casperjs,joshuafcole/casperjs,soundyogi/casperjs,RobertoMalatesta/casperjs,Andrey-Pavlov/casperjs,vladikoff/casperjs,jefleponot/casperjs,PeterWangPo/casperjs,mickaelandrieu/casperjs,vietch2612/casperjs,vladikoff/casperjs,davidwhthomas/casperjs,dj31416/casperjs,dj31416/casperjs,soundyogi/casperjs,cryptoquick/casperjs,alexbiehl/casperjs,PeterWangPo/casperjs,jamesanthonyferguson/casperjs,Andrey-Pavlov/casperjs,istr/casperjs,jamesanthonyferguson/casperjs,singhdev/casperjs,muntasir2000/casperjs,jjyycchh/casperjs,RobertoMalatesta/casperjs,pcarrier-packaging/deb-casperjs,istr/casperjs,soundyogi/casperjs