Remove `Peer certificate's common name matches local certificate's common name` behavior [JIRA: RIAK-2082]

[bsparrow435]

For development/testing purposes it is often desired to use the same cert name for 2 clusters. Support for this would be very helpful for many customers.

[Michelle's add'n]
Source: Customer request (Imprivata) via https://basho.zendesk.com/agent/#/tickets/5339

[cmeiklejohn]

Moving to 2.1.

[ssylvester87]

This issue is causing a problem for any customer attempting to use SSL for MDC v3 replication. Wildcards in the Common Name field should be supported so that multiple nodes/clusters that share all but the first domain name segment can have the same CN and be accepted by the same ACL setting in advanced.config:riak_core, but if the CN is the same between two clusters it blocks the connection.

Example:

ACL configured to allow *.bashotest.com.
Cluster 1 contains node1.bashotest.com.
Cluster2 contains node2.bashotest.com.
Node1 and node2 can have certs with their own keys and signed separately by the rootCA, but SSL handshake will still be closed by Riak because CN is the same.
This behavior was implemented for security in client-to-Riak transactions, but having Repl go through the same mechanism doesn't make sense for that use-case since it's perfectly valid for peer certs to contain the same CN.

See https://basho.zendesk.com/agent/tickets/11685