icinga: Setup icinga class, consolidate from other classes

Since the individual classes can't be used by themselves
anyway, we consolidate them into one unit.

Also rename the apache class into 'web', since that
is what it does.

The icinga-doc package is moved into the web role since
that is the only thing that apparently needs it

Change-Id: I1f111edf8e4ab77cfd953c23c36e7a9ede18e59d