DRY up fetcher configuration (#1168)

Consolidates the addition of the fetcher container to the pod into a new type FetcherConfig and takes care of serviceAccountName if not set. Also added PreStop lifecycle handler if pod set TerminationGracePeriodSeconds

test/tests/test_secret_cfgmap/cfgmap.py.template

@@ -1,5 +1,5 @@
 def main():
-	path = "/configs/default/{{ FN_CFGMAP }}/TEST_KEY"
+	path = "/configmaps/default/{{ FN_CFGMAP }}/TEST_KEY"
 	f = open(path, "r")
 	data = f.read()
 	return data, 200

test/tests/test_secret_cfgmap/empty.py

@@ -1,6 +1,6 @@
 import os
 def main():
-	cfgmap_path = "/configs/"
+	cfgmap_path = "/configmaps/"
 	secret_path = "/secrets/"
 	if os.listdir(cfgmap_path) or os.listdir(secret_path):
 		return "no", 400