Moved Test Plan to wiki page

https://github.com/tgerring/hiveapp-bitstamptrader/wiki/Test-Plan
Buttons states updated to prevent accidental double-submission

Set button state to disabled while we are waiting on a network request.
Re-enable after the request resolves or an error occurs
Re-add lougout label for extra clarity

Since API secrets are not typically recoverable, it’s extra important
that the function of this button is very clear. A confirmation box may
be useful