[Device] Add OpenUriEx player method

- 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>
[Documentation] Fixed some bugs in the docuemntation

- Readme file incorrectly referred to dleyna-server
- Replaced the term server objects with renderer objects in API.txt
- Tidied up some of the property defitions in API.txt

Signed-off-by: Mark Ryan <mark.d.ryan@intel.com>