[SPARK-5852][SQL]Fail to convert a newly created empty metastore parquet table...

[SPARK-5852][SQL]Fail to convert a newly created empty metastore parquet table to a data source parquet table.

The problem is that after we create an empty hive metastore parquet table (e.g. `CREATE TABLE test (a int) STORED AS PARQUET`), Hive will create an empty dir for us, which cause our data source `ParquetRelation2` fail to get the schema of the table. See JIRA for the case to reproduce the bug and the exception.

This PR is based on #4562 from chenghao-intel.

JIRA: https://issues.apache.org/jira/browse/SPARK-5852

Author: Yin Huai <yhuai@databricks.com>
Author: Cheng Hao <hao.cheng@intel.com>

Closes #4655 from yhuai/CTASParquet and squashes the following commits:

b8b3450 [Yin Huai] Update tests.
2ac94f7 [Yin Huai] Update tests.
3db3d20 [Yin Huai] Minor update.
d7e2308 [Yin Huai] Revert changes in HiveMetastoreCatalog.scala.
36978d1 [Cheng Hao] Update the code as feedback
a04930b [Cheng Hao] fix bug of scan an empty parquet based table
442ffe0 [Cheng Hao] passdown the schema for Parquet File in HiveContext