Allow more control over the database in the Mendix cloud

Perform vacuum, trigger rebuild of an index, download postgres log.

Any of these tasks is perfectly normal in environments where I worked before starting with Mendix. Coming from an IBM DB2 environment, completely clearing database and file storage just to trigger a database maintenance function is complete overkill.

Some features:

• Trigger a vacuum full on the entire database
• Trigger a vacuum full on an uploaded list of postgres table names
• Download postgres log.