Handle Thrown Errors with UnsafeSubscribe

... oxymoronic commit here ... adding some safety to unsafeSubscribe.
... fixes https://github.com/Netflix/RxJava/issues/1090
Merge pull request #1091 from benjchristensen/unsafeSubscribe-error-handling

Handle Thrown Errors with UnsafeSubscribe
Reconnecting ObservableExecutionHook.onCreate

Somehow this got lost in the refactorings over the past few weeks.
Merge pull request #1092 from benjchristensen/ObservableExecutionHook-onCreate

Restore ObservableExecutionHook.onCreate
[Gradle Release Plugin] - pre tag commit:  '0.18.1'.
[Gradle Release Plugin] - new version commit:  '0.18.2-SNAPSHOT'.
0.18.1
0.18.1