Initial support for getting the leader from Zookeeper.

Some tests included for making sure the JSON blob pulled from Zookeeper
is correct.

Updated client to be able to take Zookeeper json cluster config that is
currently being used in aurora (clusters.json usually located at
/etc/aurora/cluster.json).

Changed error messages to no longer have a period at the end as that was
throwing off printing of the error.

Modified samuel's ZK library slightly to stop verbose logging using a
NoOpLogger from stackoverflow.

vendor/github.com/stretchr/testify/assert/doc.go

@@ -0,0 +1,45 @@
+// Package assert provides a set of comprehensive testing tools for use with the normal Go testing system.
+//
+// Example Usage
+//
+// The following is a complete example using assert in a standard test function:
+//    import (
+//      "testing"
+//      "github.com/stretchr/testify/assert"
+//    )
+//
+//    func TestSomething(t *testing.T) {
+//
+//      var a string = "Hello"
+//      var b string = "Hello"
+//
+//      assert.Equal(t, a, b, "The two words should be the same.")
+//
+//    }
+//
+// if you assert many times, use the format below:
+//
+//    import (
+//      "testing"
+//      "github.com/stretchr/testify/assert"
+//    )
+//
+//    func TestSomething(t *testing.T) {
+//      assert := assert.New(t)
+//
+//      var a string = "Hello"
+//      var b string = "Hello"
+//
+//      assert.Equal(a, b, "The two words should be the same.")
+//    }
+//
+// Assertions
+//
+// Assertions allow you to easily write test code, and are global funcs in the `assert` package.
+// All assertion functions take, as the first argument, the `*testing.T` object provided by the
+// testing framework. This allows the assertion funcs to write the failings and other details to
+// the correct place.
+//
+// Every assertion function also takes an optional string message as the final argument,
+// allowing custom error messages to be appended to the message the assertion method outputs.
+package assert