Add some failing common tests prior to adding 'duration' to media API
Add stub for getDuration() and update relevant JsDoc
Fix problems with failing tests (no implementation yet)
Add getDuration() accessor to new media API

getDuration() accessor added to HTML5, CEHTML and Samsung new media
APIs. Added mediaplayer tests.
Add tests to ensure getRange() and getDuration() can differ
Failing test for seek sentinel when playback leaves seekable range

Since the seekable range can be less than the duration of the media,
the current implementation means that the device will seek back to the
end of the seekable range once the media has progressed >= 15 seconds
past it. This commit adds a failing test to expose the bug.
Clamp seek-sentinel target time once, not every sentinel run
getDuration() asks CEHTML object, getRange().end uses getDuration()
Revert "getDuration() asks CEHTML object, getRange().end uses getDuration()"

This reverts commit f0494e020dfb00e13d50ff1185742ddfaee780b8.
Use getDuration() to detect end of media in complete sentinel, not getRange().end
Merge pull request #191 from fmtvp/new-media-duration

Add duration property to new media API