Add a small package `mtime` which will return a defined value in place
of `time.Now()`, so that tests which depend on timing can be repeated.

Needed for object capture used in testing

So we can record a sequence of inputs then create unit tests by
playing them back.

Actually it is capturing every version fetched.

This code is temporary; will be replaced in a subsequent commit
with a version that only outputs the first version seen as 'initial'.

Read object updates and events from a file and play them back as if
they came from Kubernetes, for testing.

Essentially the test is the same, but with data captured using the
new framework. Test data is now in a yaml file rather than Go code.