Clean up Random::play_url()

Include the correct type parameter in the URL and rename the random
type parameter to random_type.

Remove unused parameters from the function call.

Should fix issue #11
Correct debug output for Stream_Playlist adds
Update the stream_playlist table to use MyISAM

InnoDB's performance is unacceptable out of the box, and there's no
clean way to batch these insertions into transactions, and stuff.

Benchmarks for 1000 inserts:
InnoDB: 54.826
MyISAM: 0.091
InnoDB transaction: 0.159

Fixes GH #14
docs/INSTALL doesn't exist any more