Secure token value

Currently bug reports generated from atom contain the token and gist repo. There should be some form of protection of the token so bug reports don't expose it. Additionally it would be preferable if other plugins don't have access to the token.

One way is to generate a random key and encrypt the token with that, the key itself could be stored as a plugin state - which I haven't investigated how secure is.

Another way is to store it in another location like custom config file in atom's config directory.

So far both approaches require building a custom UI to manage the token.