minor edits to cluster-usage doc
Merge pull request #731 from akka/wip-2527-√

Removing warning about not touching instance fields in receive
say "IO support" in docs (avoid "module")
#2097 - Adding ls-sbt for all akka projects.
#2536 - Fixing docs and making sure test artifacts are published for Akka Mailboxes Common
Adding a CONTRIBUTING.md
Update CONTRIBUTING.md

Adding workflow instructions for contributing to Akka
Don't await the write of shutdownSignal to openChannels when shutting netty, see #2535

* The multi node tests triggered shutdown ordering issue
* Not necessary to awaitUninterruptibly for the shutdownSignal to
  openChannels
Fixing version string and crossVersion string and artifact id
Removing weird artifact id in durable mailbox.rst
Minor cleanup of ls-sbt config
Docs reformatting for adding the durable mailbox test fixture
Merge pull request #733 from akka/wip-2536-√

#2536 - Fixing docs and making sure test artifacts are published for Akk...
Adding Code Reviews section and Source style section to the CONTRIBUTING.md
Update CONTRIBUTING.md

Properly indenting CONTRIBUTING.md
TestConductorSpec failure, final barrier missing, see #2440
Adding docs section in the CONTRIBUTING.md about experimental modules.
Merge branch 'wip-2373-√' of github.com:akka/akka into wip-2373-√
Merge pull request #734 from akka/wip-2373-√

Wip 2373 √
Merge pull request #736 from akka/wip-2440-testconductor-fail-patriknw

TestConductorSpec failure, final barrier missing, see #2440