DESCRIPTION
This just provides some helper methods for both token classes to use
generate_token
This will create a randomly generated 20-character token for use as a request or access token. The string is hexadecimal.
This does not check for uniqueness.
before_create
This does some checks and provides some defaults.
It tries a number of times to create a unique token using generate_token. If that fails, this method will DIE.
It will also create a secret using generate_token.
Finally, it will create a default valid_until of 1 hour from now.