Remove old binary volume scripts

We don't need the binary volume scripts anymore as this is now managed
by the volume library script.
volume: Change the prop of the permissions of the volume script

We now use the executable permission by default on the volume script.
purple-song-remote: Fix song containing an ampersand.

When song title contained an ampersand the message was not transmitted
properly with purple-remote. This is due to purple-remote misinterpreting
the ampersand it sees in the received message. We now translate these
characters to the word 'and' as a work-around for this problem.