SearchKeeper class to maintain search history of othernodes
don't require query str in constructor

pass the query string while doing search,
and forwared it to line search method
_search_keeper instance variable

pass all new searches to it,
if it has a search id (it hasn't expired it yet)
then don't process that query.
else local_search
has(id) method in SearchKeeper
[fix] HashMap<String,String> instaed of HashMap
start with hop_count 1
make the stupid IDE happy -> <> instead of <String,String>
[fix] subtract 1000 milliseconds from ttl, not 1
remove print
[fix] containsKey checks for key, not contains
[fix] also search with hop_count 16
multicast methods in Connector
pass messages types starting with 'search' to Node
_default_ttl 18s > 8+4+2+1 in SearchKeeper
handle search messages, local_search, send results, forward search