Fixed initialization of Occi::Core::Links w/ strs

`convert` in Occi::Core::Links now correctly transforms strings
into Occi::Core::Link instances. The last part of any URI/URL
is taken as `link.id` and the whole URI/URL as `link.location`.
Improved `get_by_location` on Occi::Collection

`get_by_location` can now resolve instance locations into
category locations and return appropriate categories.
Fixed JSON rendering of actions for entities

Actions available for the given entity should always be rendered
as arrays of type identifiers not full JSON representations.
Fixed action link parsing for resources

When parsing a resource link with '?action=' included in URI,
link is parsed as Occi::Core::Action and not Occi::Core::Link.
Minor version bump to 4.2.11