Added HTTP 503 error and message

src/main/java/com/omertron/themoviedbapi/MovieDbException.java

@@ -55,7 +55,11 @@ public class MovieDbException extends Exception {
         /*
          * Autorisation rejected
          */
-        AUTHORISATION_FAILURE;
+        AUTHORISATION_FAILURE,
+        /*
+         * Service Unavailable, usually temporary
+         */
+        HTTP_503_ERROR;
     }
 
     private final MovieDbExceptionType exceptionType;

src/main/java/com/omertron/themoviedbapi/TheMovieDbApi.java

@@ -121,7 +121,7 @@ public class TheMovieDbApi {
             } catch (IOException ex) {
                 throw new MovieDbException(MovieDbException.MovieDbExceptionType.CONNECTION_ERROR, null, ex);
             } catch (RuntimeException ex) {
-                throw new MovieDbException(MovieDbException.MovieDbExceptionType.CONNECTION_ERROR, null, ex);
+                throw new MovieDbException(MovieDbException.MovieDbExceptionType.HTTP_503_ERROR, "Service Unavailable", ex);
             }
         }