Interpolate service name in Nomad UI

### Nomad version
`Nomad v1.0.1`

### Operating system and Environment details
Ubuntu 18.04

### Issue
In the Nomad UI, a service's name is not interpolated if it is set to something like `${NOMAD_JOB_NAME}`.

### Job file (if appropriate)

```hcl
job "evandam-redis" {
datacenters = ["dev-usw2-dev1"]

type = "service"

group "cache" {
count = 1

network {
port "tcp" {}
}

service {
name = "${NOMAD_JOB_NAME}"
port = "tcp"

check {
name = "ping"
type = "tcp"
interval = "2s"
timeout = "2s"
}
}

task "evandam-redis" {
driver = "docker"

config {
image = "redis:5"
ports = ["tcp"]

args = [
"--port",
"${NOMAD_PORT_tcp}",
]
}

resources {
# cpu = 500 # 500 MHz
memory = 20 # 20 MB
}
}
}
}
```