Let the ActorSystem find its configuration outside of the bundle, in the OSGi etc directory, following this order:
    etc/bundle-BUNDLE_SYMBOLIC_NAME.conf
    etc/bundle-BUNDLE_ID.conf
    etc/akka.conf
    akka-actor classpath config (using the original  OsgiActorSystemFactory.actorSystemConfig method.)

Configurations fallback from the most to the less specific one.

For the moment, as I haven't found test on ActorSystem Configuration in OSGi, I did not add test for this feature.
    	modified:   akka-osgi/src/main/scala/akka/osgi/OsgiActorSystemFactory.scala
 patriknw comments commited

        * .conf, .properties, .json configuration files
        * string interpolation
        * take place of the legacy actorSystemConfig
rkuhn comments applied: no more extension  
Stress / long running test of cluster, see #2786

* akka.cluster.StressSpec
* Configurable number of nodes and duration for each step
* Report metrics and phi periodically to see progress
* Configurable payload size
* Test of various join and remove scenarios
* Test of watch
* Exercise supervision
* Report cluster stats
* Test with many actors in tree structure

Apart from the test this commit also solves some issues:

* Avoid adding back members when downed in ClusterHeartbeatSender
* Avoid duplicate close of ClusterReadView
* Add back the publish of AddressTerminated when MemberDowned/Removed
  it was lost in merge of "publish on convergence", see #2779
Fixed startup race in transport adapters #2867
Propagate statusPromise down to the actual change in throttler, see #2877

* added some missing copyright headers
Only client should issue an SSL handshake #2833
Remove LargeClusterSpec, superseded by StressSpec, see #2786
Merge pull request #940 from akka/wip-2786-cluster-stress-patriknw

Stress / long running test of cluster, see #2786
Merge pull request #1004 from drewhk/wip-2833-only-ssl-client-handshakes-drewhk

Only client should issue an SSL handshake #2833
remove extra "the" in docs
Merge pull request #1002 from akka/wip-2877-throttler-ack-patriknw

Propagate statusPromise down to the actual change in throttler, see #2877
Publish clean state when joining (PublishStart), see #2871

* The failure in JoinTwoClustersSpec was due to missing publishing
  of cluster events when clearing current state when joining
* This fix is in the right direction, but joining clusters like this
  will need some design thought, creating ticket 2873 for that
Revert "Propagate statusPromise down to the actual change in throttler, see #2877"

This reverts commit 9c1a00d02017a1786820d27a62496afb7e8285ce.
Merge pull request #1005 from akka/wip-2877-revert-patriknw

Revert "Propagate statusPromise down to the actual change in throttler, ...
Remove todo ReentrantReadWriteLock
 #2879 - updating copyright info
Merge pull request #1001 from drewhk/wip-2867-throttlertransport-failed-drewhk

Fixed startup race in transport adapters #2867
Adjust protocol pattern in LogRoleReplace for new remoting
Merge pull request #1003 from akka/wip-protocol-pattern-LogRoleReplace-patriknw

Adjust protocol pattern in LogRoleReplace for new remoting