[Device] Add OpenUriEx player method v2

added as recommended by the first review:
- strip metadata in the same way as it is done for the uri.
- I've kept the task->ut.open_uri.metadata = NULL; initialization even if it is not necessary for a better reading and understanding of the code, this field being not used in this context.

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- Add a new player interface method OpenUriEx, which is the same as
the existing OpenUri one, with an additional metadata parameter to pass
the URI description information in DIDL-Lite XML format.
- Documentation updated.
- Renderer Console python test application updated.
- Fix issue: https://github.com/01org/dleyna-renderer/issues/25

Signed-off-by: Christophe Guiraud <christophe.guiraud@intel.com>