Add basic example from #20

Author: bcardiff

examples/basic.cr

@@ -0,0 +1,18 @@
+require "../src/zeromq"
+
+# Simple server
+context = ZMQ::Context.new
+server = context.socket(ZMQ::REP)
+server.bind("tcp://127.0.0.1:5555")
+
+# Simple client
+context = ZMQ::Context.new
+client = context.socket(ZMQ::REQ)
+client.connect("tcp://127.0.0.1:5555")
+
+client.send_string("Fetch")
+
+puts server.receive_string
+server.send_string("Got it")
+
+puts client.receive_string