Imports of nats-echo command

PathSynopsis
encoding/jsonPackage json implements encoding and decoding of JSON as defined in RFC 7159.
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/nats-io/nats.goA Go client for the NATS messaging system (https://nats.io).
io/ioutilPackage ioutil implements some I/O utility functions.
logPackage log implements a simple logging package.
net/httpPackage http provides HTTP client and server implementations.
osPackage os provides a platform-independent interface to operating system functionality.
os/signalPackage signal implements access to incoming signals.
runtimePackage runtime contains operations that interact with Go's runtime system, such as functions to control goroutines.
syscallPackage syscall contains an interface to the low-level operating system primitives.
timePackage time provides functionality for measuring and displaying time.