add properties to run server on a different computer

In case of the need to run the server on a different computer than the detector host, one should set a different hostname, config_file path (default is ~det/p2_det/config/cam_data/camera.def) and tmpfs path (default is /lima_data):

• change the PilatusCamera ctor to accept new parameters for host_name, host_port, config_file and tmpfs_path
• update Pilatus.py tango plugin with new properties
• update tango plugin documentation