.Net 4 wrapper Library for MailChimp newsletter API v2

1. Add the dlls to your project
2. Add the following lines in your configuration file

<configuration>
  <configSections>
    <section name="MailChimpServiceSettings" type="MailChimp.Net.Settings.MailChimpServiceConfiguration, MailChimp.Net.Settings" />
  </configSections>
  <MailChimpServiceSettings
    apiKey="testapikey-us7"
    subscriberListId="testlistid"
    serviceUrl="https://us7.api.mailchimp.com/2.0/"
    listsRelatedSection="lists"
    helperRelatedSection="helper"/>
</configuration>
3. Code example to subscribe a newsletter with the given groupings and merge vars
```cs
IMailChimpApiService mailChimpApiService = new MailChimpApiService(MailChimpServiceConfiguration.Settings.ApiKey);
var subscribeSources = new Grouping {Name = "Subscribe Source"};
subscribeSources.Groups.Add("Site");

var couponsGained = new Grouping {Name = "Coupons Gained"};
couponsGained.Groups.Add("Coupon1");

var interests = new Grouping {Name = "Interests"};
interests.Groups.Add("Extreme Games");

var fields = new Dictionary
{
  {"GENDER", "Male"},
  {"DATEBORN", DateTime.Now.ToString(CultureInfo.InvariantCulture)},
  {"CITY", "Athens"},
  {"COUNTRY", "Greece"}
};

var response = mailChimpApiService.Subscribe("[email protected]", new List() { subscribeSources, couponsGained, interests }, fields, true);
```