Added Unit Tests and Javadocs.
Added Spring Retry logic.
Missing implementation for following APIs:
- SendMailing
- ForwardToFriend
- AddListColumn
- ListRecipientMailings
- ImportTable
- CreateQuery
- SetColumnValue
- RawRecipientDataExport
- WebTrackingDataExport
- GetFolderPath
- ScheduleMailing
- PreviewMailing
- GetMessageGroupDetails
- DCRuleset*