added build files and folders to gitignore
added build files and folders to gitignore

jsoref/PowerShell,JamesWTruher/PowerShell-1,kmosher/PowerShell,kmosher/PowerShell,bingbing8/PowerShell,bingbing8/PowerShell,KarolKaczmarek/PowerShell,kmosher/PowerShell,daxian-dbw/PowerShell,jsoref/PowerShell,JamesWTruher/PowerShell-1,bmanikm/PowerShell,bmanikm/PowerShell,PaulHigin/PowerShell,bingbing8/PowerShell,TravisEz13/PowerShell,bingbing8/PowerShell,JamesWTruher/PowerShell-1,JamesWTruher/PowerShell-1,PaulHigin/PowerShell,daxian-dbw/PowerShell,TravisEz13/PowerShell,bmanikm/PowerShell,TravisEz13/PowerShell,jsoref/PowerShell,kmosher/PowerShell,PaulHigin/PowerShell,KarolKaczmarek/PowerShell,daxian-dbw/PowerShell,kmosher/PowerShell,TravisEz13/PowerShell,daxian-dbw/PowerShell,KarolKaczmarek/PowerShell,jsoref/PowerShell,PaulHigin/PowerShell,KarolKaczmarek/PowerShell,bmanikm/PowerShell,bmanikm/PowerShell,jsoref/PowerShell,bingbing8/PowerShell,KarolKaczmarek/PowerShell