Set binaries to be executable before creating goldfish instances

Some zip tools do not preserve file permissions. Acloud sets emulator
binaries' execution permissions before it creates goldfish instances.

This commit also fixes the pylint errors in utils.py.

Test: acloud-dev create --local-instance --avd-type goldfish \
      --local-image --local-tool /tmp/sdk-repo-emulator
Bug: 153420299
Change-Id: I25214299a57d891f426fb2b003f1475f0f0c6658
5 files changed