jsonrpc: validate the connection with ping command
jsonrpc: validate the connection with ping command

Use ping command instead of Host.getHardwareInfo to
validate the status of the jsonrpc connection.

Change-Id: I56a78f55c7dd53e1632a0ce4f51c3f985997e4cc
Bug-Url: https://bugzilla.redhat.com/1457471
Signed-off-by: Simone Tiraboschi <cb03129c66ba4da7ba7044049d0f43907bf857bb@redhat.com>

oVirt/ovirt-hosted-engine-ha,oVirt/ovirt-hosted-engine-ha,oVirt/ovirt-hosted-engine-ha,oVirt/ovirt-hosted-engine-ha