fixes #65 Down command does not work with case sensitive column names.

Author: harawata

src/main/java/org/apache/ibatis/migration/operations/DownOperation.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2010-2016 the original author or authors.
+ *    Copyright 2010-2017 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -127,7 +127,7 @@ protected void deleteChange(ConnectionProvider connectionProvider, Change change
       DatabaseOperationOption option) {
     SqlRunner runner = getSqlRunner(connectionProvider);
     try {
-      runner.delete("delete from " + option.getChangelogTable() + " where id = ?",
+      runner.delete("delete from " + option.getChangelogTable() + " where ID = ?",
           change.getId());
     } catch (SQLException e) {
       throw new MigrationException("Error querying last applied migration.  Cause: " + e, e);