Send Exception to Discord

[Akkarinage]

Closes #390 .

Changes proposed in this Pull Request:

• Makes use of Discord as a method of alerting admins to page exceptions.

This will not report generic PHP errors, only errors within the application that would throw the dreaded white page of death. I.E:

This change will also continue to send exceptions to Discord on each page load until the issue is resolved. This doesn't happen often enough to be an annoyance if FluxCP is configured correctly.

[AraanBranco]

Tested, but I suggest a change, adding more information to make it easier to find the error, like this:

if(Flux::config('DiscordUseWebhook')) {
		if(Flux::config('DiscordSendOnErrorException')) {
			sendtodiscord(Flux::config('DiscordWebhookURL'), '```ansi
�[2;31mERROR�[0m
Error: '. get_class($e) .'
Exception: '. $e->getMessage() .'
File: '. $e->getFile() .':'. $e->getLine() .'```');
		}
	}

Example: