Get rid of ipaddress dependency

Use DuniterPy IPv{4,6} regexes to get rid of ipaddress dependency.

ipaddress is used in silkaj.network_tools.check_ip() to determine the IP address version. As a first step, it can be replaced with stdlib re regex module and duniterpy.constants.IPV{4,6}_REGEX regexes.

As a second step (#177 (closed)), replace silkaj.network_tools.{parse_endpoint(),endpoint_type(),check_ip()} with duniterpy.api.endpoint.{,Secured}BMAEndpoint. May be a useless step, since we will move to GVA(Endpoint).