Updated solution files to Visual Studio 2012.
Updated all NuGet packages.
Renamed IConsumer to IEventHandler.

This is done as a first step in a refactoring that separates event
handlers from command handlers. The concept is that in CQRS, there must be
exactly one command handler per command, but zero to many event handlers
per event.
This rename makes it clear that the current code base is lacking a command
handler type, and that CapacityGate should be a command handler, and not
an event handler.
Renamed Dispatcher<T> to EventDispatcher<T>.
Added CommandDispatcher,

although it's not yet used.
Added CommandHandlerConvention.

This could be combined with EventHandlerConvention for to avaoid
duplication, but for now I'll invoke the rule of three.
Added a guard against unhanlded commands,

which prompted a change of CapacityGate from event handler to command
handler.
Broke lines to stay within 80 chars width.