Clearly indicate when modifying an existing alias

Modifed kvm to output 'Updating alias' rather than 'Setting alias' when overwriting an existing alias file

fixes #2
I will push up a change to insert spaces between the variable names and the = sign to be consistent with the rest of the code.

Or were you talking about the if-as-a-ternary-operator on line 478 ? AFAIK this is idiomatic Powershell.