Don't know about easy but you have to make separate project-configurations that have different include and lib paths and then you can compile multiple configurations with
Build->Batch build . To make life a little easier when it comes to specifying different paths you could set a default path for all projects for include-path to be:
$(MAYA_SDK)\$(MAYA_VERSION)\include
And then use property sheets to set MAYA_SDK and MAYA_VERSION. MAYA_SDK could be set in one property sheet that is included for all configurations and MAYA_VERSION would need to be in a separate property sheet for each configuration per configuration where it is set to 2014 or 2013 respectively. Then when you need to compile for a new version of maya you just clone the configuration and include another property sheet that sets MAYA_VERSION to 2015.
That's one way of doing it at least, hopefully someone else has a better solution to share.
Btw, I enjoyed your Mechanical Rigging class :)