Move Get-SourceArguments to Else
Merge pull request #425 from RichiCoder1/list-performance-change

Improve Chocolatey List LocalOnly performance
(GH-426) List returns packages & versions as object

This allows returning a hash of all packages/versions found through the list
command. This only does so when $returnOutput = $true as redirecting output
from a process slows this command down and it needs to be able to return very
quickly in scenarios where grabbing everything locally.