ApkInfo: Improve error for bad .apk files

Provide a more specific error, including the output from aapt.
diff --git a/devlib/utils/android.py b/devlib/utils/android.py
index ce1ab0b..0cdd2b0 100644
--- a/devlib/utils/android.py
+++ b/devlib/utils/android.py
@@ -135,7 +135,11 @@
         _check_env()
         command = [aapt, 'dump', 'badging', apk_path]
         logger.debug(' '.join(command))
-        output = subprocess.check_output(command)
+        try:
+            output = subprocess.check_output(command, stderr=subprocess.STDOUT)
+        except subprocess.CalledProcessError as e:
+            raise HostError('Error parsing APK file {}. `aapt` says:\n{}'
+                            .format(apk_path, e.output))
         for line in output.split('\n'):
             if line.startswith('application-label:'):
                 self.label = line.split(':')[1].strip().replace('\'', '')