When a Nomad agent starts and loads jobs that already existed in the
cluster, the default template uid and gid was being set to 0, since this
is the zero value for int. This caused these jobs to fail in
environments where it was not possible to use 0, such as in Windows
clients.
In order to differentiate between an explicit 0 and a template where
these properties were not set we need to use a pointer.
This eases adoption of the jobspec package by other projects (e.g. terraform nomad provider, Lavant). Either by consuming directy as a library (hopefully without having go mod import rest of nomad) or by copying the package without modification.
Ideally, this package will be published as an independent module. We aren't ready for that considering we'll be switching to HCLv2 "soon", but eitherway, this seems like a reasonable intermediate step if we choose to.
