per-template token override

Just like a template can override global `wait { }` settings, it would be nice if it could override the global `token` settings, to allow usage of different tokens for different templates with a single consul-template instance.

No files, tests, or entry points are named in the issue. Start by locating the global token configuration and template-specific wait-setting handling, then determine how configuration is parsed and applied per template. Done should mean each template can select token settings independently while a single consul-template instance continues to render all templates.

Written by the indexing model from the issue text.