Make ssh1 and ssh2 fetch_host_key return the same structure

This was indirectly causing the crash reported here:
http://seclists.org/nmap-dev/2014/q4/332

ssh1.fetch_host_key now returns a table with the full_key value
containing a key as it would be output by ssh-keygen. The previous value
named full_key is now named "key".

nselib/ssh1.lua

@@ -107,7 +107,8 @@ fetch_host_key = function(host, port)
       fp_input = mod:tobin()..exp:tobin()
 
       return {exp=exp,mod=mod,bits=host_key_bits,key_type='rsa1',fp_input=fp_input,
-              full_key=exp:todec()..' '..mod:todec(),algorithm="RSA1",
+              full_key=('%d %s %s'):format(host_key_bits, exp:todec(), mod:todec()),
+              key=('%s %s'):format(exp:todec(), mod:todec()), algorithm="RSA1",
               fingerprint=openssl.md5(fp_input)}
     end
   end