Explicits usage of sum from math package

Avoids conflicting names
Adds 3 more mock tags
Adds 2 more mock tags
Adds debug messages
FIX buggy list iteration for one-element list
FIX conflicting var/func names
FIX playlist cleaning erasing itself
Adds play_order field to tracks

Adds prints to debug annoying "TypeError: <Response 207 bytes [200 OK]> is not JSON serializable"
occuring when flushing new Playlist entry to database
FIX issue with json (previous commit)
FIX "TypeError: datetime.datetime(2013, 5, 8, 23, 37, 3, 279124) is not JSON serializable"

The list of playlists is now fetchable! :)
Minor update
Adds author name for new playlist, removes some prints
Naming of playlist, new playlist JSON

* Naming of the newly created playlist is no more based on random numbering, but
on actual playlist id: playlist_<playlist.id>
* The returned json of the newly created playlist is no more encapsulated into a
"playlist" entry, but all the playlist fields are returned directyl at
top-level: { "<playlist-fieldN>" : "<valueN>", etc. }
FIX global name 'Person' undefined
Factorizes playlist dict creation by using common function to_dict(playlist)

Some vars renaming.
Sets default values to options, some code clean up.

Removes deprecated comments, rewrites pl_generator description to reflect
actual implementation.
Adds support of user provided title in pl_generator
FIX bugs

* FIX UnicodeDecodeError: 'ascii' codec can't decode byte [...]
* AttributeError: 'ResultSet' object has no attribute 'playlist'

Else:
* Sets datetime.microsecond = 0 to remove microseconds from iso 8601 format
FIX trailing microseconds in iso 8601 format
Merge branch 'groupSuggestion'