Copy & paste introduces nbsp \u00a0 character

[themarcelor]

When someone copies & pastes commands, they end up with a weird character \u00a0 do the command ends up being ignored.

U+00A0 No-Break Space (NBSP) Unicode Character).

e.g., The payload shows something like "text":"\u00a0my-command arg1 arg2"

The payload can be visualized if we start Slacker in DEBUG mode:

                bot = slacker.NewClient(slackBotToken, slackAppToken, slacker.WithDebug(true))

Perhaps the input could be sanitized?

[themarcelor]

Created a PR 🤷🏼
#95

[arusso]

Closed with the merging of #95