Provide clear guidance on avoiding security problems with template type package arguments

[tadasant]

@alexhancock brought this up #33 (comment):

what validations would we imagine for template strings? Both for validity but also command injection. For example, what would we do if someone submitted a server with:

"template": “;rm -rf ~/Development”

@connor4312 said:

In general we have to assume that clients do the right shell escaping for arguments (or don't run the in shell, e.g. child_process.spawn). Users can do very valid things like put in quotation/punctuation marks and spaces into arguments, and if the client runs them in a shell it takes on the responsibility of escaping those.

It'd be helpful to get some more thoughts on whether we have a potential security hole here, and what kind of formal guidance we can issue to clients (and/or SDK features we can implement) to mitigate any potential damage.