jsonrpc: reducing logging noise

Removed log entires which are not critical to understand how requests
are processed. Fixed few spelling mistakes.

Change-Id: I37f6262b7e9918467c7c547b62aacb5d207094af
Signed-off-by: pkliczewski <piotr.kliczewski@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/30516
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>