Moved Studio images from img/ directory to images/ directory

OPEN-304
Don't use 'test' db for mysql since it's reserved.

This db name is reserved and used by mysql installations. This can cause
conflicts when trying to populate our own 'test' database on mysql.
Add created_on and created_by to asset metadata storage.
https://openedx.atlassian.net/browse/PLAT-278
Fix the DJFS dependency.
Merge pull request #5954 from edx/benp/mysql56-test-updates

Don't use 'test' db for mysql since it's reserved.
Merge pull request #5953 from edx/jeskew/created_by_on_addition

Add created_on and created_by to asset metadata storage.
Merge pull request #5955 from edx/sanchez/fix-djfs-dependency

Fix the DJFS dependency.
Merge pull request #5941 from edx/studio-images

Moved Studio images from img/ directory to images/ directory
disable "go to payment button" on click (ECOM-643)