Incorrect handling of configuration failures in SAL netconf connector

Version: 1.1.0-SNAPSHOT (Boron) (master branch)

SAL netconf connector handles invalid configuration just by logging warning message what casues that RESTCONF response indicates result code 200 OK.

Possible solution:
https://git.opendaylight.org/gerrit/gitweb?p=netconf.git;a=blob;f=netconf/sal-netconf-connector/src/main/java/org/opendaylight/netconf/sal/connect/netconf/sal/tx/WriteCandidateTx.java;h=4001c3186b385d16b376421256c9ac66c3dba224;hb=refs/heads/master#l192

In the method onSuccess() there's a check isSuccess(). If the isSuccess returns false, then the warning message is logged. But there should be used the same handling as in the method onFailure().

See attached logs for more details.