Instead of instructing users to do static calls
in to Unleash, she should instead be allwed to
specify the log provider as an option to Unleash.
This commit introduces the "getLogger" option,
a function responsible for creating a logger.
Will know tell the user if the toggle name is already
in use by an active feature toggle or an archived toggle.
Also brings lates unleash-frontend fix, which prevents an
invalid form from submitting.
closes: #290, #291
