Allow main class to be called by UnifiedStorage

Author: aliphys

src/UnifiedStorage.h renamed to src/Arduino_UnifiedStorage.h

@@ -28,7 +28,7 @@
         #include "FATFileSystem.h"
     #endif 
 
-class UnifiedStorage {
+class Arduino_UnifiedStorage {
     public:
         virtual int begin() = 0;
 
@@ -50,5 +50,7 @@ class UnifiedStorage {
 #endif
 
 
+extern Arduino_UnifiedStorage UnifiedStorage;
+
 #endif