releasetools: Initalize logger when signing.

Other modules have switched to logging module. sign_target_files_apks.py
needs to init the logger to get the logs.

Test: Run `sign_target_files_apks.py -v`. Check outputs.
Test: Run `check_target_files_signatures.py -v`.
Change-Id: Ic68c019f6fb14840561885f1194ad6efdfdb7d82
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index a07f67f..85897c2 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -102,6 +102,7 @@
 import copy
 import errno
 import gzip
+import logging
 import os
 import re
 import shutil
@@ -121,6 +122,8 @@
   sys.exit(1)
 
 
+logger = logging.getLogger(__name__)
+
 OPTIONS = common.OPTIONS
 
 OPTIONS.extra_apks = {}
@@ -180,11 +183,8 @@
 
   # skipped_prefixes should be one of set/list/tuple types. Other types such as
   # str shouldn't be accepted.
-  assert (isinstance(skipped_prefixes, tuple) or
-          isinstance(skipped_prefixes, set) or
-          isinstance(skipped_prefixes, list)), \
-              "Invalid skipped_prefixes input type: {}".format(
-                  type(skipped_prefixes))
+  assert isinstance(skipped_prefixes, (set, list, tuple)), \
+      "Invalid skipped_prefixes input type: {}".format(type(skipped_prefixes))
 
   compressed_apk_extension = (
       ".apk" + compressed_extension if compressed_extension else None)
@@ -816,7 +816,7 @@
   result = dict()
   for codename in codenames:
     codename = codename.strip()
-    if len(codename) > 0:
+    if codename:
       result[codename] = api_level
   return result
 
@@ -926,6 +926,8 @@
     common.Usage(__doc__)
     sys.exit(1)
 
+  common.InitLogging()
+
   input_zip = zipfile.ZipFile(args[0], "r")
   output_zip = zipfile.ZipFile(args[1], "w",
                                compression=zipfile.ZIP_DEFLATED,