This fixes a test failure in Vertica involving the date_trunc function
which expect timestamp strings to be explicitly cast as a timestamp.

Fixes #5085

Driver loading previously was very dependent on what code clojure
compiled first. If the Oracle driver was loaded before the plugin
directory was examined, it would result in the Oracle driver never
being loaded. This is due to clojure code only being loaded once when
required and the driver loading code being free floating code that is
only evaled when the namespace is loaded.

This commit switches that code to be in an -init-driver function that
is invoked when the driver is required. This ensures that regardless
of code loading order, the driver will be available if it's present.

This commit also includes code to fail the build if requested to test
on an engine when that engine's driver is not available. Previously if
you set ENGINES to "h2,oracle" but had no Oracle driver in the plugins
directory, the test would succeed, but only test against H2.

Include fields metadata for Saved Questions 'virtual' DB

Nested Queries + dashboard params fixes 

Put images in loading/init screen

Heroku stdout can get overwhelmed by the output causing a deploy to
fail

Minor code cleanup 

* only show the title and description if in a dashboard

* fix tests

Fix drag to filter for nested queries

Fix drag-to-filter and Safari clip-path issue

Test for #5406 *cough*

Don't send/show archived cards in pulses (#5224)

Add clarifying info about Metabot to docs, fix some typos. Fixes #4604

Fix some colorization not being disabled when MB_COLORIZE_LOGS=false

Don't run H2 in AUTO_SERVER mode

Set appropriate JVM options for E2E tests

Fix Jest OOM errors

Disable E2E tests that are failing / being converted to use Jest&Enzyme [WIP]

Correct indecies to indices in migration file

Nested queries