Return calculated assets from update_credits.

inara.py

@@ -58,7 +58,7 @@ class InaraSession(CachedSession):
   def update_credits(self, credits):
     soup = self.get_soup(CMDR_URL)
     if not self._inara_is_logged_in(soup):
-      return False
+      return None
 
     oass = int(soup.find(id='oassinput')['value'])
     data = {
@@ -70,7 +70,7 @@ class InaraSession(CachedSession):
     }
     r = self.post(CMDR_URL, data=data)
     r.raise_for_status()
-    return True
+    return credits + oass
 
   def update_location(self, location):
     data = {