Older version of docker doesn't support the exec api Env and WorkingDir options.
Support these versions by doing the same we already do with the k8s driver: use
the `toolbox exec` command that will set the provided Env, change the cwd to the
WorkingDir and the exec the wanted command.
Before kubernetes 1.14 nodes were labeled with the "beta.kubernetes.io/arch"
label instead of the "kubernetes.io/arch".
Current k8s version (v1.15) labels nodes with both labels but it's
deprecated and will removed in future versions.
At driver start get the current k8s api version and choose the right label to
use as node selector based on it.
This was already defined in the config but not implemented in the executor and
drivers.
All the containers defined in the runtime after the first one will be "service"
containers. They will share the same network namespace with the other containers
in the "pod" so they can communicate between themself on loopback
Also if they are logically part of the runservice the names runserviceExecutor
and runserviceScheduler are long and quite confusing for an external user
Simplify them separating both the code parts and updating the names:
runserviceScheduler -> runservice
runserviceExecutor -> executor
