ES6 Refactor

#####TODO

• Fix Known Issues.
• Restore/Fix Frag Abandonment
• Need ProtectionModel Detect system
• Add back in object name and media type for log system.
• Add API to set buffer pruning at MediaPlayer level. Can not directly assign to const value anymore. Make sure we expose all static const values that we may need access externally.
• Make sure all var list are unchained when there is any assignment for consistency.
• Add setInstance to add flexibility to Factory E.g Unit test
• Change Unit test folder structure to confirm to mocha test/unit.....
• Clean up the unit test helpers folder
• Sort out unit test runner for mocha
• Need more advance way to extend objects instead of brut force merge.
• Make sure there are no unused imports in any class.
• DOCUMENTATION!!!
• Get BOLA integrated

#####Known Bugs

• External text tracks are not initializing properly. Fragmented is fine.
• addBufferMetrics buffer target and virtual buffer level needs to be looked at.

#####Challenges, Changes, and Considerations

• Extensible code where needed. We can use the new extend method to override methods in any class or singleton like we did with context but even more useful as you can partial. But not true extensibility.

#####Build/Unit Tests

• ASAP stand up current test in new environment and add to test coverage.