Add string safety to application name parsing (#275)

* Add string safety

* A more calming debug message

Author: Peter Giacomo Lombardo

instana/util.py

@@ -392,7 +392,7 @@ def determine_service_name():
 
         # Get first argument that is not an CLI option
         for candidate in sys.argv:
-            if candidate[0] != '-':
+            if len(candidate) > 0 and candidate[0] != '-':
                 basename = candidate
                 break
 
@@ -449,7 +449,7 @@ def determine_service_name():
             except ImportError:
                 pass
     except Exception:
-        logger.debug("get_application_name: ", exc_info=True)
+        logger.debug("non-fatal get_application_name: ", exc_info=True)
     finally:
         return app_name