Refactor confusing getting of IDs from Term objects

The method getEntityId was missleading as this is not what we
actually get. We get the numeric ID.

This pokes other classes to reduce the ammount of times we use
these numeric IDs. I could not nor do I want to touch and replace
all numeric IDs in a big patch. I think this already is a helpful
step in the right direction. Obviously more patches must follow
but shouldn't block this patch.

Change-Id: I895c24ea880ad4aafa2fca48c99b87691574b7e5
Merge "Refactor confusing getting of IDs from Term objects"