Refactor bot commands in Philbot

[royh02]

Currently we use discord.Client for our bot client that can be updated to a more feature rich discord.ext.commands.Bot. This will free up the cluttered on_message check that we currently use for commands and provide more modularity as well as documentation for commands. The documentation can then be accessed through a help command on the discord server as well.

Since discord.ext.commands.Bot inherits discord.Client, theoretically, this transition will work.