In case Pod names ever change without changing endpoint addresses.

We don't need a binary-to-text encoding for the hash, we just test
the binary result. We also don't need to sort []Endpoint or hash
Service.

InitTemplates() takes a map of template paths to file paths, and
returns a map of parsed template to file paths.

Add WriteTemplate(), which takes a parsed template and a file path,
and generates VCL at the path from a spec and the template. Meant
for iteration on the map returned by InitTemplates().