[FAB-8506] Log which capabilities are on

A fairly obvious oversight in the capabilities code is that nowhere are
the capabilities which are on actually logged.  This is a trivial fix,
and will help serviceability considerably.  This applies for both
ordererr and peer.

Sample log output:

[common/capabilities] Supported -> DEBU 09b Orderer capability V1_1 is
    supported and is enabled
[common/capabilities] Supported -> DEBU 09c Channel capability V1_1 is
    supported and is enabled

Change-Id: Idccf7f4f0265d88d77374e42406997d18ee5c247
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

common/capabilities/capabilities.go

@@ -44,6 +44,7 @@ func newRegistry(p provider, capabilities map[string]*cb.Capability) *registry {
 func (r *registry) Supported() error {
 	for capabilityName := range r.capabilities {
 		if r.provider.HasCapability(capabilityName) {
+			logger.Debugf("%s capability %s is supported and is enabled", r.provider.Type(), capabilityName)
 			continue
 		}