Added new interface: Reader.
The HmReader implements the Reader interface.
The XmlReader class implements the Reader interface.
Added the gmock to the testsLib.pri.
Added new class: NulLReader.
Replaced the readDb function with the createDbReader in the DatabaseReader.
Replaced the readIn function with the createInReader in the DatabaseReader.
Added new interface: Writer.
The XmlWriter implements the Writer interface.
Defined the FilePtr and StreamPtr types.
Flushing the stream after using it in the XmlWriter.
Replaced the writeDb function with the createWriter in the DatabaseReader.
Removed the db_ member from the DatabaseReader.
Renamed the DatabaseReaderTest to DatabaseReaderIntegrationTest.
Added new test suite: DatabaseReaderTest.
Implemented the createDbReader, createInReader and createWriter related tests.
Merging with the dbReader branch. Fixes #22.