Removed bind mount of .ssh in runcontext

Removed bind mount of .ssh in runcontext

Previously the .ssh directory of the invoking user was bind mounted
into the build container. This behavior is now removed. The ssh keys
in the user's .ssh is however *copied* into the container if, and only
if, the RSYNC_CONNECT_PROG environment variable has been set as this
indicates the need to tunnel rsync traffic over (presumably) ssh. In
this case the keys may actually be needed.

In both cases the .ssh/config file will be updated with the
   StrictHostKeyChecking=no
option to prevent failure due to the ssh confirmation dialogue.

Change-Id: Ic2ecc9d7a9abfa796bdfa6aaa8cde0dcb632d76e
Signed-off-by: Stefan K. Berg <stefan.k.berg@ericsson.com>
(cherry picked from commit bae859e2a47befeb3c6a97988dc778daf66e37bd)