Fix exclude-databases for collector package

[sysadmind]

The pg_database collector was not respecting the --exclude-databases flag and causing problems where databases were not accessible. This now respects the list of databases to exclude.

• Adjusts the Collector create func to take a config struct instead of a logger. This allows more changes like this in the future. I figured we would need to do this at some point but I wasn't sure if we could hold off.
• Split the database size collection to a separate query when database is not excluded.
• Comment some probe code that was not useful/accurate

Signed-off-by: Joe Adams [email protected]

[sysadmind]

also, this fixes #588

[sysadmind]

@SuperQ Good idea. I removed the commented code.

[macmiranda]

@sysadmind you planning on fixing the conflicts?