clarify error when no project.json in the path
clarify error when no project.json in the path

also correct help information

fixes #356

jaredpar/cli,mlorbetske/cli,schellap/cli,stuartleeks/dotnet-cli,blackdwarf/cli,marono/cli,borgdylan/dotnet-cli,FubarDevelopment/cli,jaredpar/cli,naamunds/cli,ravimeda/cli,mlorbetske/cli,AbhitejJohn/cli,AbhitejJohn/cli,danquirk/cli,jkotas/cli,EdwardBlair/cli,svick/cli,weshaggard/cli,Faizan2304/cli,mylibero/cli,marono/cli,borgdylan/dotnet-cli,danquirk/cli,blackdwarf/cli,gkhanna79/cli,borgdylan/dotnet-cli,gkhanna79/cli,AbhitejJohn/cli,jkotas/cli,nguerrera/cli,nguerrera/cli,naamunds/cli,mylibero/cli,danquirk/cli,krwq/cli,dasMulli/cli,Faizan2304/cli,krwq/cli,danquirk/cli,weshaggard/cli,anurse/Cli,schellap/cli,MichaelSimons/cli,Faizan2304/cli,JohnChen0/cli,jonsequitur/cli,blackdwarf/cli,schellap/cli,weshaggard/cli,MichaelSimons/cli,MichaelSimons/cli,jonsequitur/cli,JohnChen0/cli,mylibero/cli,johnbeisner/cli,marono/cli,stuartleeks/dotnet-cli,jaredpar/cli,harshjain2/cli,MichaelSimons/cli,JohnChen0/cli,jkotas/cli,johnbeisner/cli,jonsequitur/cli,naamunds/cli,weshaggard/cli,schellap/cli,dasMulli/cli,livarcocc/cli-1,ravimeda/cli,livarcocc/cli-1,EdwardBlair/cli,naamunds/cli,gkhanna79/cli,krwq/cli,harshjain2/cli,svick/cli,jkotas/cli,marono/cli,mylibero/cli,MichaelSimons/cli,blackdwarf/cli,johnbeisner/cli,harshjain2/cli,stuartleeks/dotnet-cli,krwq/cli,schellap/cli,schellap/cli,mylibero/cli,nguerrera/cli,krwq/cli,borgdylan/dotnet-cli,borgdylan/dotnet-cli,jaredpar/cli,stuartleeks/dotnet-cli,mlorbetske/cli,ravimeda/cli,JohnChen0/cli,jaredpar/cli,FubarDevelopment/cli,nguerrera/cli,stuartleeks/dotnet-cli,danquirk/cli,dasMulli/cli,AbhitejJohn/cli,svick/cli,naamunds/cli,FubarDevelopment/cli,mlorbetske/cli,jonsequitur/cli,jkotas/cli,gkhanna79/cli,jaredpar/cli,FubarDevelopment/cli,gkhanna79/cli,EdwardBlair/cli,marono/cli,livarcocc/cli-1,weshaggard/cli