nfs: added enable/disable switch to embeded portmat

In some cases we do not want to start embedded portmap
even if OS does not provide one.

introduced property

nfs.enable.portmap=true/false

Default it true for backward compatibility

Acked-by: Gerd Behrmann
Target: trunk
Require-book: no
Require-notes: yes
libdcap: remove redundant code

The dcap code is since middle of January 2013 has
its own repository:

https://github.com/dCache/dcap

Acked-by: Gerd Behrmann
Target: trunk
Require-book: no
Require-notes: no