Filemap: add debugging facility

Filemap: add debugging facility

Add the 'log' parameter to the Filemap* classes to allow passing the logger
object where the debugging prints will go. This is similar to what we have in
the BmapCopy module. Also add the same parameter to 'BmapCreate' and make sure
that 'bmaptool' passes its logger to 'BmapCreate', which then passes it to
'Filemap*' objects, where we use it for debugging.

This makes sure that '--debug' triggers debugging messages from 'Filemap*'
ojects.

Change-Id: Idc9686edc4809856720481f79e37887d29a8b0df
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>