Try to support mysql servers with version < 4.1 (related to #304)

Changes:

- Depend on module `semver` to match mysql server versions
- Change `HandshakeInitializationPacket` to support previous version
- Change `ClientAuthenticationPacket` to support previous version
- Change `Handshake` to use `Auth.scramble323` instead of `Auth.token` when <4.1
- Change other packets to support old versions

Not sure (but done):

- How to detect if it is FieldPacket or OkPacket. For now it checks if RowDataHeader was sent before.

For testing this is in branch `fix304`.