Update license_finder to 6.0.0 and adjust its configuration

With version 6, license_finder has changed the 'whitelist' option to
'permit'.

aruba.gemspec

@@ -29,7 +29,7 @@ to make testing commandline applications meaningful, easy and fun.'
   spec.add_runtime_dependency 'thor', '~> 1.0'
 
   spec.add_development_dependency 'json', '~> 2.1'
-  spec.add_development_dependency 'license_finder', '~> 5.3'
+  spec.add_development_dependency 'license_finder', '~> 6.0'
   spec.add_development_dependency 'minitest', '~> 5.10'
   spec.add_development_dependency 'pry-doc', '~> 1.0'
   spec.add_development_dependency 'rake', '~> 13.0'

doc/dependency_decisions.yml

@@ -4,7 +4,7 @@
   - :who: 
     :why: 
     :when: 2016-05-09 14:57:58.000000000 Z
-- - :whitelist
+- - :permit
   - MIT
   - :who: 
     :why: 
@@ -14,7 +14,7 @@
   - :who: 
     :why: 
     :when: 2015-04-28 13:39:28.340867782 Z
-- - :whitelist
+- - :permit
   - BSD
   - :who: 
     :why: 
@@ -34,17 +34,17 @@
   - :who: 
     :why: 
     :when: 2016-04-19 21:38:58.571635580 Z
-- - :whitelist
+- - :permit
   - ruby
   - :who: 
     :why: 
     :when: 2016-04-19 21:40:01.747535503 Z
-- - :whitelist
+- - :permit
   - New BSD
   - :who: 
     :why: 
     :when: 2016-12-07 14:54:49.587491547 Z
-- - :whitelist
+- - :permit
   - Simplified BSD
   - :who: 
     :why: