added PackageVersion arg
added new arg for package version
corrected the logic in setting package in argument parser
changed InstallCommand, CommandFactory to respect package version
package version and special version will be extracted in PackageReference
added tests
moved PackageReferenceTests to separate file
update paths to use chocolatey conventions

update the install path to look at the chocolatey_bin_root env param.
seeing runtime permissions issues in running things from `appdata`
because of powershell execution policy set higher up the chain