Transaction and campaign URLs
Add Ecommerce example to the Demo project.
Refactor transaction builder.
Improvements when to create new sessions.
Separate per request, session and static parameters into different methods.
Goals and Ecommerce implementation.
Implement support for event tracking.
Improvements and spelling of API documentation.
Bug fixes to campaign tracking (but still not showing in the Piwik server)
Comment out unused constants to remove compiler warnings.
Merge commit 'e3a1cbed58ca1ef1296e7525e1abef6b1f39fbc9' into noafn

Conflicts:
	PiwikTracker/PiwikTracker.h
	PiwikTracker/PiwikTracker.m
fix warnings