[DBClientConfig] Rename the file to DBTablesConfig.

This patch only renames the (source and header) file name.
The change of the class name will be soon after.
[DBClientConfig] Rename the class name to DBTableConfig.

The DBClient's sub class is a set of tables in a DB.
So the new directly expresses that.

Signed-off-by: Takuro Ashie <ashie@clear-code.com>

Conflicts:
	server/src/DBTablesConfig.h
	server/test/testDBTablesConfig.cc
	server/test/testFaceRestIncidentTracker.cc
Merge pull request #406 from project-hatohol/rename-dbtables-config-2

The DBClient's sub class is a set of tables in a DB.
So the new directly expresses that.

This pull request is retry of #396 (b62d6f5fb85769e3ee8c7dc492645d958901c76c).