refactor tests

* extract method to test if the contact header is valid
* remove useless variables
* add test to ensure the server replies with a Contact Header
* add test stub to ensure the client sends a Contact Header
make cla API similar to the net API

* add callback parameter to cla.createServer
* add toolkit helper function to check if an argument is defined
remove space on empty object literals
refactor cla.createServer

* add helper function to check for the existence of server options
* change main function to acknowledge option arguments
* add toolkit helpers to detect object and function types
add testing support for server options
add connect function to the CLA interface

* add CLA connect function
* point createConnection function to connect function
* remove now useless tests
* add test to ensure a Contact Header is exchanged by both sides