Module settings for default key and algorithm

[bdw429s]

Would it make sense to introduce optional module settings to configure the default key and algorithm to use for all operations? That would simplify the API as I wouldn't have to pass in the key and algorithm every time I called the service.

moduleSettings = {
  jwt : {
    key : 'myKey',
    secretIsBase64 : true,
    algorithm : 'HS512'
  }
};

I can send over a pull for this if you like.

[andrew-dixon]

@bdw429s Sounds good, pull request away :-)