SYNCT-276: Extend the configuration to give fine grained control (#117)
* SYNCT-276: Added the "preferredClient" field to the ClassConfig and added the Serializable interface to the config classes
* SYNCT-276: Changed the approach to determine the preferred client (first try to use the class preferred client) and updated the unit tests
* SYNCT-276: Added support of specific clients configuration
* SYNCT-276: Added the possibility to set specific clients credentials