Campaign Sections fix

Allow campaign sections to be specified (serialized) as a dictionary.
Campaign Creation fix / add

Fixed DataMember for BaseTemplateID.  Added CampaignCreateTrackingOptions class.
Exception handling adjustment

IMHO, the exception should present the true nature of the problem at the outermost layer if possible.  I was getting "500 Internal Server Error" as the primary message which wasn't helpful.  I mean it may help debug the API, but it won't help the end user debug their code.
MailChimpManager date helper functions

Provided helper functions to allow users to process DateTime's for use in the APIs.
Merge pull request #37 from AndrewKoransky/master

campaign adjustments - optional helper functions, optional exception handling change