Proposal: Make Location a subclass of Network Object

Rationale:

1. Location has an id and name attribute. These attributes are described Network Object, so making Location a subclass 
of Network Object prevents us from defining an id and name specific to the Location.

2. The 'locatedAt' relation relates a Network Object to a Location. I can imagine a future extension where NML allows 
Locations within a Location (e.g. one Location describing a country, another Location describing a city, a third 
Location describing a specific server room). If Location is a subclass of Network Object, such relations may be allowed 
in the future. Otherwise, it is not possible to make such extension.