Limit tab completion of scan command to scans with installed components (#74)

* scans without installed requirements dont tab-complete

* added meets_requirements functions to classes

* updated tests

* added check for None case

pipeline/recon/web/waybackurls.py

@@ -8,6 +8,7 @@ from luigi.contrib.sqla import SQLAlchemyTarget
 
 from .targets import GatherWebTargets
 from ...tools import tools
+from ..helpers import get_tool_state
 from ...models.endpoint_model import Endpoint
 
 import pipeline.models.db_manager
@@ -48,6 +49,15 @@ class WaybackurlsScan(luigi.Task):
         self.db_mgr = pipeline.models.db_manager.DBManager(db_location=self.db_location)
         self.results_subfolder = Path(self.results_dir) / "waybackurls-results"
 
+    @staticmethod
+    def meets_requirements():
+        """ Reports whether or not this scan's needed tool(s) are installed or not """
+        needs = ["waybackurls"]
+        tools = get_tool_state()
+
+        if tools:
+            return all([tools.get(x).get("installed") is True for x in needs])
+
     def requires(self):
         """ WaybackurlsScan depends on GatherWebTargets to run.