Add Lists getters

[apocheau]

I added the ability to retreive informations about a specific list or list all lists.
Just pay attention to the "ListInfo.modules" array, which is not implemented.

[basiliscus]

There must be no space or newline here, as it breaks the link in Dokka

[basiliscus]

Hi apocheau,

Thank you for the contribution. I've left some comments and will merge the changes as soon as the issues fixed.

[apocheau]

Hello basiliscus and thanks for your reply.
It's the first time i use Kotlin so i appreciated your observations and will follow your guidelines.
For modules, i'll try to find more info about it, otherwise, i'll remove it.
It seems there is a lack of information about this field:

http://developer.mailchimp.com/documentation/mailchimp/reference/lists/#read-get_lists_list_id
"modules": {
"type": "array",
"title": "Modules",
"description": "Any list-specific modules installed for this list.",
"readonly": true,
"example": [
""
],
"links": null
}

Finally, do you have kind of roadmap or stuff you are working on ?

[basiliscus]

Finally, do you have kind of roadmap or stuff you are working on ?

No, I do not have any plans on improving the library. However, contributions are welcome: I will be merging pull requests and releasing new versions.