Fix token expire time

Author: Ben Pedrick

src/main/java/com/opentok/api/OpenTokSDK.java

@@ -67,9 +67,9 @@ public String generate_token(String session_id, String role, Long expire_time, S
 		    throw new OpenTokException(role + " is not a recognized role");
 
 		if(expire_time != null) {
-		    if(expire_time < new Date().getTime())
+		    if(expire_time < System.currentTimeMillis() / 1000)
 				throw new OpenTokException("Expire time must be in the future");
-		    if(expire_time > (new Date().getTime() + 604800))
+		    if(expire_time > (System.currentTimeMillis() / 1000 + 604800))
 				throw new OpenTokException("Expire time must be in the next 7 days");
 			data_string_builder.append("&expire_time=");
 			data_string_builder.append(expire_time);