A config with no distros respects forced requirements

[MHendricks]

Addresses #35

Checklist

• I have read the CONTRIBUTING.md document
• I formatted my changes with black
• I linted my changes with flake8
• I have added documentation regarding my changes where necessary
• Any pre-existing tests continue to pass
• Additional tests were made covering my changes

Types of Changes

• Bugfix (change that fixes an issue)
• New Feature (change that adds functionality)
• Documentation Update (if none of the other choices apply)

Proposed Changes

Fixes this bug and also modernizes the license_file setting in setup.cfg

Testing:

1. Set HAB_PATH to your tests\site_main.json
2. Use the URI not_set/no_distros. This is a config that doesn't inherit and doesn't define distros.
3. Run hab -r aliased dump not_set/no_distros -v. You will now see aliased listed in the versions section.

WARNING:hab.solvers:Forced Requirement: aliased
Dump of FlatConfig('not_set/no_distros')
----------------------------------------------------------
name:  no_distros
uri:  not_set/no_distros
aliases:  as_dict inherited as_list as_str global
versions:  aliased==2.0
----------------------------------------------------------

4. If you remove -r aliased from the command you won't see any versions. This is the correct behavior.

Dump of FlatConfig('not_set/no_distros')
-------------------------------------------------
name:  no_distros
uri:  not_set/no_distros
versions:
-------------------------------------------------