Fix SqlBuilder.OrWhere method which was actually yielding an 'AND WHERE' statement.

Dapper.SqlBuilder/SqlBuilder.cs

@@ -143,7 +143,7 @@ public SqlBuilder Where(string sql, dynamic parameters = null)
         
         public SqlBuilder OrWhere(string sql, dynamic parameters = null)
         {
-            AddClause("where", sql, parameters, " AND ", "WHERE ", "\n", true);
+            AddClause("where", sql, parameters, " OR ", "WHERE ", "\n", true);
             return this;
         }