Update the year in the Copyright string (#320)

Templatize the copyright string and use a build variable to set the year for use across the entire app.

How changes were validated:
Tested with English and French and with different dates.

src/Calculator/pch.h

@@ -21,6 +21,7 @@
 #include <sstream>
 #include <concrt.h>
 #include <regex>
+#include <string>
 
 // C++\WinRT Headers
 #include "winrt/base.h"