manager runs on Mac, and other openpilot for PC fixes (#1037)

* use the openpilot/persist directory on PC

* manager runs on mac

* sim runs w/o carla

* fix params location in test

* that rmtree can fail and it's okay

* refactor params clear functionality

* set PARAMS_PATH

common/api/__init__.py

@@ -1,13 +1,13 @@
 import jwt
 import requests
 from datetime import datetime, timedelta
-
+from common.basedir import PERSIST
 from selfdrive.version import version
 
 class Api():
   def __init__(self, dongle_id):
     self.dongle_id = dongle_id
-    with open('/persist/comma/id_rsa') as f:
+    with open(PERSIST+'/comma/id_rsa') as f:
       self.private_key = f.read()
 
   def get(self, *args, **kwargs):