default proc for type-casted-binds to be logged by AR's LogSubscriber

so that we do not have PS param values nil-ed e.g. `['created_at', nil]`

with JDBC we do not need the type-casted pieces as we're not using them
... having a proc which is used when debug logging is gets them right
the only draw-back is it will only work on recent AR 5.0/5.1 (>= 5.0.6)
(support for a loggic proc was introduced at rails/rails#29623)

lib/arjdbc/abstract/core.rb

@@ -64,7 +64,7 @@ def log(sql, name = "SQL", binds = [], type_casted_binds = nil, statement_name =
             sql:               sql,
             name:              name,
             binds:             binds,
-            type_casted_binds: type_casted_binds,
+            type_casted_binds: type_casted_binds || -> { type_casted_binds(binds) }, # works since AR 5.0.6
             statement_name:    statement_name,
             connection_id:     object_id) { yield }
       rescue => e