import vmtest should not create dirs or initialize log

[Scott Moser]

when working with a merge to add image information, i found/remembered that simply importing vmtest ends up writing some output to the console and creating a tempdir and a log.

Kind of obnoxious. Would be better if it did not.

Example:
$ python3 -m tests.vmtests.image_sync query --max=1 /srv/images/ release=precise
2016-06-20 17:15:37,765 - tests.vmtests - INFO - Logfile: /tmp/vmtest-2016-06-20T171537.765169.log . Working dir: /tmp/vmtest-2016-06-20T171537.765169
precise amd64/hwe-p 20160610.1 boot-initrd
precise amd64/hwe-p 20160610.1 boot-kernel
precise amd64/hwe-p 20160610.1 root-image.gz

[Scott Moser (smoser)]

fyi, if we fix this might want to fix tools/jenkins-runner to use
   python3 -m tests/vmtests/image_sync
rather than
   PYTHONPATH=$PWD python3 -m tests/vmtests/image_sync.py