Use a vendor directory for repeatable builds - fixes #816

This is using godep to manage the vendor directory.

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

@@ -0,0 +1,44 @@
+// Package mock provides a system by which it is possible to mock your objects
+// and verify calls are happening as expected.
+//
+// Example Usage
+//
+// The mock package provides an object, Mock, that tracks activity on another object.  It is usually
+// embedded into a test object as shown below:
+//
+//   type MyTestObject struct {
+//     // add a Mock object instance
+//     mock.Mock
+//
+//     // other fields go here as normal
+//   }
+//
+// When implementing the methods of an interface, you wire your functions up
+// to call the Mock.Called(args...) method, and return the appropriate values.
+//
+// For example, to mock a method that saves the name and age of a person and returns
+// the year of their birth or an error, you might write this:
+//
+//     func (o *MyTestObject) SavePersonDetails(firstname, lastname string, age int) (int, error) {
+//       args := o.Called(firstname, lastname, age)
+//       return args.Int(0), args.Error(1)
+//     }
+//
+// The Int, Error and Bool methods are examples of strongly typed getters that take the argument
+// index position. Given this argument list:
+//
+//     (12, true, "Something")
+//
+// You could read them out strongly typed like this:
+//
+//     args.Int(0)
+//     args.Bool(1)
+//     args.String(2)
+//
+// For objects of your own type, use the generic Arguments.Get(index) method and make a type assertion:
+//
+//     return args.Get(0).(*MyObject), args.Get(1).(*AnotherObjectOfMine)
+//
+// This may cause a panic if the object you are getting is nil (the type assertion will fail), in those
+// cases you should check for nil first.
+package mock