Improve documentation for use of templates

[svanoort]

Needs to be in the first example, tutorial, and more common in example files and advanced guide so people can see it in action. Have had a couple questions on this and for every question asked there are probably 3 people who went away frustrated.

Templating should be treated as part of the most common use for docs purposes, not just an advanced feature.

[svanoort]

Good examples:

• Login & Request for Github or Reddit APIs + a few sample API calls
• Show use with hardcoded parameters for credentials + passing via cmdline
• Demonstrate use of environment variables and generators for test series (got stripped out of examples in revisions)

[svanoort]

Note: add to the quickstart and README.md file.

Edit: tie this to 1.7.x because it probably will need changes with #101 and #75