fixes #3712

fixes #3507

This prevents malformed JSON from getting saved in a slice's params. It
also prevents the issue described in #3507 from happening though as a
result malformed slices will render using default control values.

A shortcut to make it easy to refresh a table's schema

1. avoid exports is not defined error
2. per jordan's suggestion, update .babelrc only use airbnb presets

* Reorders MANIFEST.in

* Includes the translations dir in MANIFEST

Dialect's has_table method requires connection as the first argument, not engine (https://github.com/zzzeek/sqlalchemy/blob/master/lib/sqlalchemy/engine/interfaces.py#L454). Instead, we can use engine's has_table method that handles the connection for us (https://github.com/zzzeek/sqlalchemy/blob/master/lib/sqlalchemy/engine/base.py#L2141). Alternatively, we could call engine.dialect.has_table(engine.connect(), ...).

Move all translation config to superset/translations

In `assets/static` we have a symlink pointing to `docs/_build/html`
which is .gitignored and missing in the repo since we don't want the
html-generated docs in the repo, meaning the symlink is broken

Having the symlink broken creates issues with pip-compile somehow.

Adding a dummy file here addresses that

So we stop confusing people that thinks we do DDL.

Fix #3761

update to 1.9

I have built and pip installed with latest cryptography.

* [time table] add tooltip to sparkline

* [time table] open link in new tab

* [time table] add back Mustache