* upgrade celery to 4.0.2
* using Redis for unit tests (sqla broker not supported in Celery 4)
* Setting Celery's soft_time_limit based on `SQLLAB_ASYNC_TIME_LIMIT_SEC` config
* Better error handling in async tasks
* Better statsd logging in async tasks
* show [pending/running] query status in Results tab
* systematically using sqla NullPool on worker (async) to limit number
of database connections
* sql_lab.py: compress via utils
* utils.py: added zlib_compress and zlib_compress_to_string
* core.py: converted to use zlib_decompress_to_string; renamed uncompress to decompress in utils.py
* utils_tests.py: added test for compress/decompress
* fixed broken utils test; removed redundant code and empty lines from utils.py
* utils.py: corrected docstrings, removed unnecessary 'else'
* removed yet another superfluous else
* Implement table name extraction tests.
* Address comments.
* Fix tests and reimplement the token processing.
* Exclude aliases.
* Clean up print statements and code.
* Reverse select test.
* Fix failing test.
* Test JOINs
* refactore as a class
* Check for permissions in SQL Lab.
* Implement permissions check for the datasources in sql_lab
* Address comments.
* Change in files
* Renamin files and folders
* cleaning up a single piece of lint
* Removing boat picture from docs
* add superset word mark
* Update rename note in docs
* Fixing images
* Pinning datatables
* Fixing issues with mapbox-gl
* Forgot to rename one file
* Linting
* v0.13.0
* adding pyyaml to dev-reqs
