Add support for attribute RESOLUTION

Andrea
Add dump test of playlist with resolution.

Andrea
Fix function documentation.

Andrea
Make resolution a tuple (h, v) of integers.

Andrea
The 2 tests had the same function name,
so only the 2nd was actually executed.
Moved the dump test to the correct area.

Andrea
Merge pull request #19 from audetto/master

Add attribute RESOLUTION
Merge pull request #4 from globocom/master

merge with upstream