Fixed defender's objective tracking flag carrier ID

Removed DEFENDERS_OBJECTIVE_ONFLAG and DEFENDERS_OBJECTIVE_ONCARRIER and all associated updates/calls from base_id.lua
	- defenders objective should point to cap always to avoid tracing the flag carrier 
fortressforever/fortressforever#58
Minor thing, but I'm uncertain about prepending your name to comments. I know that it's (inconsistently) done throughout the FF source code, but I'm not sure it's all that useful and might be better handled by version control (git blame would provide the same/better info).