More features and Less Sketch Implementations!

With this release, I address three general features or implementations.

• VideoPlayer controls: Through the MasterPlayerController class, functions such as stopVideo, resumeVideo, pauseVideo, and playVideo have been implemented and/or reworked due to added functionality.
• Progress tracking: Currently downloaded assets now post numeric progress changes [0, 100] of type in through the handler handleDownloadProgress within the MasterPlayerController class. Refer to Readme for more details.
• Download queue: Assets to be downloaded are now placed in a queue, which are processed on demand. Note that populating the VideoCollectionManager with more than one asset does not mean that they will be downloaded immediately. It is the developer's responsibility to explicitly enqueue the video using the functions provided in the MasterPlayerController class.
• Supporting functions: File check functions, such as isAssetDownloaded and isAssetInDownloadQueue have been added to determine a video's download state.

If there is any feedback, questions, or suggestions, please open them in the Issue tracker. :)