timestamps changed from uint64_t to int64_t

There were cases in the code where time calculations and comparisons were overflowing and causing connection instability.  This will keep time calculations within expected ranges.

service/SoftwareUpdater.hpp

@@ -167,7 +167,7 @@ public:
 	 *
 	 * @return True if we've downloaded and verified an update
 	 */
-	bool check(const uint64_t now);
+	bool check(const int64_t now);
 
 	/**
 	 * @return Meta-data for downloaded update or NULL if none