Use option dependencies for summary

Using option dependencies is cleaner than chaning how an option
is enabled.

Reference: #2842
Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

src/summarycode/score.py

@@ -65,7 +65,7 @@ class LicenseClarityScore(PostScanPlugin):
     ]
 
     def is_enabled(self, license_clarity_score, **kwargs):
-        return license_clarity_score or kwargs.get('summary2')
+        return license_clarity_score
 
     def process_codebase(self, codebase, license_clarity_score, **kwargs):
         if TRACE:

src/summarycode/summarizer2.py

@@ -57,7 +57,9 @@ class ScanSummary(PostScanPlugin):
         PluggableCommandLineOption(('--summary2',),
             is_flag=True, default=False,
             help='Summarize license, copyright and other scans at the codebase level.',
-            help_group=POST_SCAN_GROUP)
+            help_group=POST_SCAN_GROUP,
+            required_options=['classify', 'license_clarity_score']
+        )
     ]
 
     def is_enabled(self, summary2, **kwargs):