Add on config file the location path for each categories with multi-connector support for the same extension

[cgourdin]

ex:
vm/ --< Meta model infrastructure kind: compute --< default connector factory

compute/ --< Meta model infrastructure kind: compute --< Connector factory like org.myotherconnector.ConnectorFactory

In the configuration file it will be like this :
vm=https://categoryScheme#compute
compute=https://categoryScheme#compute org.myotherconnector.ConnectorFactory

With this use case we could use multiple connectors on the same extension and category :
vm/ ==> use the first connector (the default)
compute/ ==> use the second connector (org.myotherconnector.ConnectorFactory)

MART may be updated with this use case to route the factory correctly.