Add support for filtering install locations via softwareName

Currently, `Install-ChocolateyPackage` and `Install-ChocolateyInstallPackage` have the `softwareName` parameter in their examples, but the parameter is not documented (chocolatey/docs#308) and the parameter is not implemented (it just goes to `$ignoredArguments`). The parameter is also in the `chocolateyInstall.ps1` as created by the new command.

I don't think there is an issue yet for implementing this parameter yet.

It needs to be added to both powershell functions as a parameter, and documented in those functions. Then, it needs to get passed back into the C#, presumably in the same way `ChocolateyPackageInstallLocation` is used. Then finally it can be used to filter the registry snapshot.

Start with the Install-ChocolateyPackage and Install-ChocolateyInstallPackage PowerShell functions, then trace how ChocolateyPackageInstallLocation is passed into the C# code and used with the registry snapshot. Document softwareName in both functions and carry it through the implementation so install locations can be filtered by it. Done means the parameter is no longer ignored and the related examples and function documentation are accurate.

Written by the indexing model from the issue text.