Initial configuration for Bandit and Prospector

With this configuration it should be feasible to achieve a perfect score
without contortion.

Rules skiped for Bandit:
B101: assert_used
B104: hardcoded_bind_all_interfaces
B404: import_subprocess
B603: subprocess_without_shell_equals_true
B606: start_process_with_no_shell
B607: start_process_with_partial_path

Rules skiped for pylint:
- too-many-statements
- too-many-locals
- too-many-function-args
- too-many-arguments
- too-many-branches
- bare-except
- protected-access
- no-else-return

.bandit

+[bandit]
+exclude: sshuttle/tests
+skips: B101,B104,B404,B603,B606,B607

.prospector.yml

+strictness: medium
+
+pylint:
+  disable:
+    - too-many-statements
+    - too-many-locals
+    - too-many-function-args
+    - too-many-arguments
+    - too-many-branches
+    - bare-except
+    - protected-access
+    - no-else-return
+
+pep8:
+  options:
+    max-line-length: 79
+
+mccabe:
+  run: false