numericality: Do not run all submatchers

This commit changes the numericality matcher so that when running
submatchers, the matcher will stop on the first one that fails instead
of running them all. Since all of the submatchers modify the same
record, running all of them is actually bad since it could possibly make
the failure message confusing (since the record will be in a mixed
state).

lib/shoulda/matchers/active_model/validate_numericality_of_matcher.rb

@@ -549,11 +549,7 @@ def update_diff_to_compare(matcher)
         end
 
         def first_failing_submatcher
-          failing_submatchers.first
-        end
-
-        def failing_submatchers
-          @_failing_submatchers ||= @submatchers.select do |submatcher|
+          @_failing_submatchers ||= @submatchers.detect do |submatcher|
             !submatcher.matches?(@subject)
           end
         end