Revert "[TASK] Add default value for remaining SQL columns"

This reverts commit 6f69e5cb09b2727ba50bdb8b8607d4487d1b072d.

As per http://dev.mysql.com/doc/refman/5.6/en/blob.html :
> BLOB and TEXT columns cannot have DEFAULT values.
[BUGFIX] Allow null for page flexform
[TASK] Update vhs 2.0 namespaces