travis: Fail build if vulture finds dead code

.travis.yml

@@ -63,6 +63,9 @@ script:
 ## Check that all python is properly formatted. Fail otherwise.
 - python -m black --check .
 
+## Check that there is no dead python code
+- python -m vulture .
+
 ## Run unit tests and generate coverage data
 - cd monkey  # This is our source dir
 - python -m pytest --cov=. # Have to use `python -m pytest` instead of `pytest` to add "{$builddir}/monkey/monkey" to sys.path.

monkey/monkey_island/Pipfile

@@ -42,6 +42,7 @@ flake8 = "==3.9.0"
 pytest-cov = "*"
 isort = "==5.8.0"
 coverage = "*"
+vulture = "==2.3"
 
 [requires]
 python_version = "3.7"

monkey/monkey_island/Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "3057235b1e85593ee307d9e5a2e0d15e26f13437bb709529303c7c900d3c7b41"
+            "sha256": "6734e0c45321194a1ec4ac2e91af8efb9b9dd9e7f02af146d01219dc64847a51"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -1447,6 +1447,14 @@
             "index": "pypi",
             "version": "==20.4.3"
         },
+        "vulture": {
+            "hashes": [
+                "sha256:03d5a62bcbe9ceb9a9b0575f42d71a2d414070229f2e6f95fa6e7c71aaaed967",
+                "sha256:f39de5e6f1df1f70c3b50da54f1c8d494159e9ca3d01a9b89eac929600591703"
+            ],
+            "index": "pypi",
+            "version": "==2.3"
+        },
         "zipp": {
             "hashes": [
                 "sha256:3607921face881ba3e026887d8150cca609d517579abe052ac81fc5aeffdbd76",