[Tizen] Content API - Part 3

Added support for Tizen filters (AttributeFilter only). The rest (Range and Composite) are coming later.

Added also support for media type specific attributes for audio, video and image types.

Changed some types to more convenient ones f.ex timestamp to string.

Added filtering features to examples/content.html test page.
Merge pull request #278 from poussa/content-3

[Tizen] Content API - Part 3