store module and unit test for store
add basic watch implementation
add notification struct
add notification function to store module and add unit-test
make store system communicate with raft
add delete handler
fix start as a follower(problem with election timeout) and join command
add watch function and distinguish sensetive and non-sentive command
change mux to http, parse the url by handler
election new leader and rejoin works
fix generate path (generate to slash)
add snapshot feature
clean up the codes
add node expiration feature
change command api to support expiration feature
recovery check experiation
add web interface
add new files
fix a expiration bug
add tls fetures