fixed uniqueid so that it is a function as expected by index.js and elsewhere

also added test for uniqueid. only test that two calls to uniqueid return unique enties. had to modify the output slightly and added a counter to the system otherwise two back to back calls would return the same value.

tests/lib/uniqueid.js

@@ -0,0 +1,12 @@
+var tape = require("tape")
+
+var uniqueid = require("../../lib/uniqueid.js")
+
+tape("test uniqueid", function(t) {
+  var a = uniqueid()
+  var b = uniqueid()
+
+  t.notEqual(a,b,"Two calls to uniqueid produce different values")
+
+  t.end()
+})