fix(client): dramatically simplify scaling logic

fixes the current issues in master with `deisctl install/uninstall platform`.

```
><> deisctl uninstall platform
Destroying service containers...
deis-cache@1.service: inactive
deis-logger@1.service: inactive
deis-registry@1.service: inactive
deis-controller@1.service: inactive
deis-builder@1.service: inactive
deis-router@1.service: inactive
Service containers destroyed.
><> deisctl install platform
Scheduling data containers...
deis-database-data.service: loaded
deis-registry-data.service: loaded
deis-logger-data.service: loaded
deis-builder-data.service: loaded
Data containers scheduled.
Scheduling service containers...
deis-database@1.service: loaded
deis-cache@1.service: loaded
deis-logger@1.service: loaded
deis-registry@1.service: loaded
deis-controller@1.service: loaded
deis-builder@1.service: loaded
deis-router@1.service: loaded
Service containers scheduled.
><> deisctl scale foo=1
Error: Could not find unit template for foo
```

Create() now takes a slice of strings, so this needs to be
```go
 c.Create([]string{component + "@" + strconv.Itoa(numExistingContainers+i+1)})
```