Fixes for issue #1
  - Wrapped registration of the marker plugin in a
registerVideoJsMarkersPlugin method with a check for videojs load and a
recursive timeout
  - Moved the code for initializing markers into its own
initializeMarkers method with a check for player duration and a
recursive timeout
  - Added a forceInitialization setting which immediately attempts
initialization if true
Merge pull request #4 from AlfrescoLabs/master

Fixes for issue #3