[hotfix] More js flask-admin related fixes

[hotfix] making modal window accessible

Adding missing file

v1.6.2

[hotfix] gunicorn version 19.4.? has issues serving static files

More conservative connection pooling

NullPool to reduce mysql connections

Merge pull request apache#782 from airbnb/close_conn

[core] Closing db connection during execution

Merge pull request apache#774 from mrorii/rst-links

Replace markdown links with rst links

Reducing sqla connection pool