0.16.0

• Fix append_array for the Kanrisuru::Command class with negated check on Array type.
• Add to_f method for Kanrisuru::Command and Kanrisuru::Result with unit test cases.
• Refactor lsblk_version into seperate command namespace with it's own parser.
• Add functional test cases for several core modules.
• Add return_value option to stub_command! method for non-result return methods. These are few and far between, but need to be tested appropriately.
• Refactor several core modules with use of command calls for legibility.
• Fix several issues with create_user, update_user, and delete_user.