Updated downloading message to display actual feed URL.
Renamed Nuget API Feed variable to KRE_FEED in line with termonology from windows kvm.ps1
Only set KRE_FEED when it is not already set, allowing the user to override if necessary (in line with kvm.ps1)
Fixed return value of _kvm_find_latest and terminated kvm when _kvm_find_latest does not find a valid version in the feed
Merge pull request #404 from graemechristie/patch-1

Fix KVM references
Modified the command 'kvm alias foo bar' to allow alias 'foo' to be set to the verison of alias 'bar' when bar is an existing alias