adopt go1.13 stdlib errors
update module path
add isc license
add go1.13 to go.mod
add HTTPClient interface
.
add remote addr to heartbeat log
use cleanhttp to fix keepalives file descriptor bug
wip
fix deadlock, simplify service error handling
store host, role for logs
add host, role info to logs
fix data race
update github.com/pkg/errors to v0.8.1
fix lock contention bug
improve logs
remove database, keep state in memory
add client timeout Expect a client to respond with 200 OK in less than 10 seconds, even if the job may take much longer.
fix linter warning
add github.com/pkg/errors checksum to go.sum
fix context cancel bug