Fixed strange behavior of TypesafeConfigReader trait.

Typesafeconfig trait was using TypesafeConfigReader object in #readJDBCSettings and #readConnectionPoolSettings. Because of this, TypesafeConfigReader#readJDBCSettings and #readConnectionPoolSettings couldn't load files other than application.conf.
Fixed test
Merge pull request #96 from tototoshi/fixed-typesafeconfig-reader-load-different-file

Fixed a bug which TypesafeConfigReader always calls the default reader method(which just reads only application.conf)