Support automated client API token generation

Please create a method to generate a client based token outside the web based GUI (e.g. using the API itself or a command line tool).

We are creating a script to automate our entire deployment process. From setting up a SPanel account to creating new databases, sub-domains, and email accounts for that account. Currently this is not possible as we are forced to manually create a client based token (using the GUI) after the SPanel account is created.

But we could fully automate the key creation if we could create a client based token using an admin API action (perhaps `admin/createusertoken`) or through a CLI on the server (`spanel createusertoken $user$`).