Better exception when files are unaccessible

In some cases the Hadoop filesystem API will throw NullPointerException when trying to access files that have moved.
We'd want to catch those and give a better error message.
```
Caused by: java.lang.NullPointerException
at org.apache.hadoop.fs.FileSystem.globStatus(FileSystem.java:1043)
at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.listStatus(FileInputFormat.java:211)
at parquet.hadoop.ParquetInputFormat.listStatus(ParquetInputFormat.java:395)
at parquet.hadoop.ParquetInputFormat.getFooters(ParquetInputFormat.java:443)
at parquet.hadoop.ParquetInputFormat.getGlobalMetaData(ParquetInputFormat.java:467)
```

**Reporter**: [Julien Le Dem](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=julienledem) / @julienledem

_{**Note**: *This issue was originally created as [PARQUET-20](https://issues.apache.org/jira/browse/PARQUET-20). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

首先，对照堆栈跟踪中显示的 Hadoop FileSystem.globStatus 和 FileInputFormat.listStatus 调用，跟踪 parquet.hadoop.ParquetInputFormat.listStatus、getFooters 和 getGlobalMetaData。确定无法访问或已移动的文件在哪里以 NullPointerException 的形式出现，然后验证由此产生的失败是否会改为报告有用的错误；该 issue 未指明测试文件。

由索引模型根据 Issue 内容生成。