Merge pull request #79 from stevenzwu/master

issue 78: added new constructor that takes in ClassLoader arg
[Gradle Release Plugin] - pre tag commit:  '1.2.3'.
[Gradle Release Plugin] - new version commit:  '1.2.4-SNAPSHOT'.
deprecated ill-defined createInjector() API that has bad side effect of creating a new LifecycleInjector object