Version 1.3.1 - Infinite reconnect bugfix

This commit fixes the issue with infinite reconnects, whose fix was introduced (untagged) before v1.3.0, and which reappeared in 1.3.0.
This bug would sometimes cause a seemingly infinite number of reconnect attempt messages to be sent to the text channel, along with the generation of a massive log full of constant messages related to these commands. This would occasionally not even obey stop, persisting until CadenceBot was stopped on the server or removed from the Discord guild.

I fixed this bug originally by adding a timeout between reconnects (30 seconds). However, as part of the upgrade to version 1.3.0, that is, as part of fixing #14 (multiple server support), this functionality was made specific to the voice channel (that is, each voice channel has its own timeout), and thus broken (by, specifically, the code which prevented the equivalent of null-pointer errors resulting from a lack of set reconnect information about the particular voice channel).
This version fixes that functionality - Reconnects are now disallowed within 30 seconds of any initiation of playback.