Merge pull request #39 from mdevaev/master

Common image for apps
use explicit package versions when building images
fixed tests
gitignored temporary test files
Bump version: 3.1.0 → 3.2.0
migrated to elog>=1.1
api: use threaded gunicorn workers
migrated to dominator >=14.1
updated test fixtures
Bump version: 3.2.0 → 3.3.0
Merge pull request #40 from nikicat/master

use explicit versions when building images
.travis.yml: cleanup
tox: disabled pylint test; pylint warnings reduced
migrated to dominator >=15
logging: use jsonlog to print structured logs to file instead of elog
Bump version: 3.3.0 → 3.4.0
Merge pull request #41 from nikicat/master

Migrated to Dominator >=15; use jsonlog instead of elog
use jsonformatter instead of python-json-logger for json logs
Bump version: 3.4.0 → 3.5.0
Merge pull request #42 from nikicat/master

use jsonformatter instead of python-json-logger for json logs