Handle illegal errors thrown from plugin
Merge pull request #898 from benjchristensen/safe-subscriber-plugin-error-handling

Handle illegal errors thrown from plugin
[Gradle Release Plugin] - pre tag commit:  '0.17.0-RC2'.
[Gradle Release Plugin] - new version commit:  '0.17.0-RC3-SNAPSHOT'.
GroupBy Unit Test from #900

https://github.com/Netflix/RxJava/issues/900
Merge pull request #901 from benjchristensen/groupBy-unit-test

GroupBy Unit Test from #900
Fixed NullPointerException that may happen on timeout
Merge pull request #902 from johanhaleby/master

Fixed NullPointerException that may happen on timeout