It's questionable that a default license makes any sense from a legal perspective.
If the tool created the license without the user choosing it, then it may not even be applicable.
Best to let the user choose their license with intent.
These tests were time-dependent and would start failing in 2018
when the golden files still have the copyright year of 2017.
Fix by hard-coding the year 2017 for the purpose of these two tests
to ensure reproducible builds.
Fixes#503
* Refactoring code that unnecessarily declares a map before making it.
* Cleaning up gpl3 formatting to match other licenses.
* Adding functionality that allows specifying custom license header
and text in cobra config.
* Using license header and text as templates so that they can use
template variables (for custom and gpl3 licenses).
* Adding ability to specify no license.
* Adding custom license example to README.
