Domain not available to register SSL certificate after app is created

When using a Bash script to create an app, promote the main domain to primary, and register an SSL certificate for that domain, the certificate registration doesn't work. (See issue #38 for the reason behind the command under "Remove invalid line at end of variable"). This is the script:

```bash
# Create the app
app_json_object_raw=$( atomic apps:create "$account_id" "$site_url" "$site_url" )

# Remove invalid line at end of variable
app_json_object=$( sed '/^\[/d' <<< "$app_json_object_raw" )

# Get app id from json object
app_id=$( jq '.[ "id" ]' <<< "$app_json_object" )

# Get domain id from json object
domain_id=$( jq '.[ "aliases" ][ 1 ][ "id" ]' <<< "$app_json_object" )

# Set primary domain
atomic apps:domain:make-primary "$app_id" "$domain_id"

# Register SSL certificate
atomic ssl:le:register "$account_id" "$site_url"
```

When trying to register the certificate I get this error:

```
In RequestException.php line 113:

Client error: `POST https://mgmt.pagely.com/api/ssl/letsencrypt/register` resulted in a `422 Unprocessable Entity` response:
{"status":"ERROR","body":{"domain":{"messages":["Domain(s) starter2.staging.thirdpress.com must be hosted at pagely and (truncated...)
```

I also get an error when trying to register the certificate for the domain through the Atomic control panel after that command is run. I presume this is something to do with timing, as if I wait a few minutes then I can issue the certificate through the control panel.