Get the permissions for a given target.
There's two different formats the key can be in
1) just the target. eg. 'mytaskflow'
In this case, all the other values are defaulted.
2) as a series of parameter and value pairs, seperated by a ; character
For example 'target=; permissionClass=MyClass;
In this case we tokenize what we passed and work out
what we were given. Any required value not provided will