address review comments for 0.0.9 upgrade

* remove code for submodules as they aren't used by obfs4proxy
* clean repo before zipping source tree
* allow CI failure for verification (new releases can only be verified
  after uploaded)
2 jobs for obfsproxy-0.0.9 in 9 minutes and 31 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #3031
build

00:02:25

 
  Test
failed #3032
allowed to fail
test

00:07:05

 
Name Stage Failure
failed
test Test
    main()
File "./verify-obfs4proxy.py", line 14, in main
verified = verify(version, for_android=False)
File "./verify-obfs4proxy.py", line 38, in verify
reference_file_name])
File "/usr/lib/python3.5/subprocess.py", line 271, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['wget', '--no-verbose', 'https://dl.bintray.com/briarproject/org.briarproject/org/briarproject/obfs4proxy/0.0.9/obfs4proxy-0.0.9.zip', '-O', 'reference/obfs4proxy-0.0.9.zip']' returned non-zero exit status 8
ERROR: Job failed: exit code 1