fix longname returned in HS_DESC control events

According to control spec, longname should not contain any spaces and is
consists only of identy_digest + nickname

added two functions:
* node_get_verbose_nickname_by_id()
* node_describe_longname_by_id()
remove node_describe_by_id() function

This function is not used anymore
add test for node_get_verbose_nickname_by_id
add test case for node_get_verbose_nickname