* fix several tests that were using akka.remote.netty.tcp config
* replace akka.tcp with akka in more places
* some doc cross references to remoting.md
* Add CopyrightHeader support for sbt-boilerplate plugin.
* Add CopyrightHeader support for `*.proto` files.
* Add regex match for both `–` and `-` for CopyrightHeader.
* Add CopyrightHeader support for sbt build files.
* Update copyright from 2018 to 2019.
* Testing of singleton leaving
* gossip optimization, exiting change to two oldest per role
* hardening ClusterSingletonManagerIsStuck restart, increase ClusterSingletonManagerIsStuck
* Adjust cross DC gossip probability for small nr of nodes in a DC
When a Dc is being bootstrapped the initial node has no local peers and
can not gossip if it selects a local gossip round. Start at a
probability of 1.0 for a single node cluster and move down 0.25 per node
until a 5 node DC is reached then use the cross-data-center-gossip-probability
* Fix cross DC gossip selecting of oldest members
This used to select the members based on the sort order members in
Gossip (by address) rather than by upNumber
