Allows to load PITR and Map-resolvers from fqdns

This patch adds 2 functions in lisp_lib.c:
-lispd_get_address5 ( 5 because it accepts 5 arguments) that converts an address either from an IP or an hostname string. Once it has convert the hostname into a list of sockaddr, iterate over these sockaddr and passes them to the function passed as a callback.
-copy_addr_from_sockaddr which is self explanatory

Here is an output of config loading.
DEBUG: Configuration file: RLOC probing not defined. Setting default values: RLOC Probing Interval: 30 sec.
DEBUG: converted addr_str [intouch-ams-mr-ms-1.rloc.lisp4.net] to address [217.8.98.42]
DEBUG: Added intouch-ams-mr-ms-1.rloc.lisp4.net to map-resolver list
DEBUG: converted addr_str [tdc-mr-ms.rloc.lisp4.net] to address [193.162.145.50]
DEBUG: Added tdc-mr-ms.rloc.lisp4.net to map-resolver list
DEBUG: Added 193.162.145.46 to proxy-etr list
DEBUG: converted addr_str [eqx-ash-pxtr.rloc.lisp4.net] to address [69.31.31.98]
DEBUG: Added eqx-ash-pxtr.rloc.lisp4.net to proxy-itr list