Merge pull request #1 from constantcontact/master

Collect updates from master Repo
Added overload for ConstantContact.GetCampaignTrackingClicks

The overload was added to allow for pagination to be used. I also edited the method definitions for the pagination overload of GetClicks in CampaignTrackingService.cs and ICampaignTrackingService.cs to remove the DateTime parameter as it was unused.
Cleaned up overload of ConstantContact.GetCampaignTrackingClicks

Removed the use of the dateTime parameter in the pagination overload as it was no longer needed.
Changed type of LinkID in ClickActivity class to String

This resolves issues with URL ids being too large to fit in a 32-bit integer. Similar IDs are handled as strings everywhere else in the wrapper.
Finished removing created date from pagination

createdSince is not used for pagination in ConstantContact.GetClicks(), so I have removed it.
Merge pull request #13 from kramerg/master

Fix type conversion issue with ClickActivity.LinkId