Refactoring to add non-hive engines
  * remove hive specific operations/system-queries from client.js
  * add APIs to engine Executers to get metadatabas (databases/tables/partitions/columns)
  * add API to determine jobname to Executer
  * fix to specify database name to execute queries every time

And fix to use different interval times for MR queries and system queries on hiveserver2
 * to reduce wait time in system queries (like GetTables)

Squashed commit of the following:

commit e3771fa92ffee143a9ffb4b8c85b573472d5fb85
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 18:22:55 2014 +0900

    remove debug prints

commit 468b4311d430796a6f021703d46969bcea43e2f2
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 18:07:12 2014 +0900

    fix database change clause

commit df78e1482937466ca9355b046800f62689576bff
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 18:00:32 2014 +0900

    remove debug prints

commit 7d8bde5ab4d2dd784b23e2f53d596bd77f9ad80c
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 17:50:57 2014 +0900

    add debug output

commit 07ead3a6b0b9bd1d7d21a2d1a903d021bb609955
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 17:50:23 2014 +0900

    fix to use Fetcher correctly

commit 97f9c103ffe61238a51b93f7458365137e13ff37
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 17:29:42 2014 +0900

    fix to return empty string for NULL comment

commit 0e98fdced7e4078ed07b6334726f480f391f77dd
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 17:26:47 2014 +0900

    fix to format results from HiveServer2

commit 7024c443363ff36ec1df71b7121a7dcdb2b8c6e1
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 16:39:47 2014 +0900

    fix w/ fetcher

commit 8b07ab62b4d5d2bb7683b7a28ef8341036c4a427
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 16:34:38 2014 +0900

    fix

commit 0ebe4b69d259c46b1f40ea3e4b4f3dd199108895
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 16:13:23 2014 +0900

    fix to specify schema(dbname) for tests on HiveServer2

commit 3ca08633754b1bf9ccd51df30b911c5a4ac18184
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 16:12:55 2014 +0900

    fix name as right name for HiveServer2

commit 38c5066203b4e7fc7eeff3964759a52f5e6a8bbc
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 13:27:54 2014 +0900

    Fetcher.wait() is not needed
      * In monitor supported environment (including incoming HS2), "stop" operation can kill jobs
        * and then, query stops and fetch returns immediately as failure
      * In non-monitor environment, lasting fetch uses one of file handle (tcp connection) or several times of rpc
        * not so large resource

commit f4693bfcd672f206be194c5ab40d4e7a2159d5d9
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Wed Jan 22 13:23:58 2014 +0900

    fix to use different timeouts for query execution and other statements

commit 98632e06b6cffd5ffc4731b7b546fbccb48d83c6
Author: TAGOMORI Satoshi <tagomoris@gmail.com>
Date:   Tue Jan 21 21:27:54 2014 +0900

    Wrap up high level engine APIs
     * separate shib/client and app.js from engines result formatting
     * hide differences of engines API details in each engine implementations
     * generate jobname of query w/ query engines

    not tested.