More catalogs + Supporting functionality

[brickbots]

Working to add a couple more catalogs, but wanted to make the growing number of catalogs more usable

• [x] Ability to choose active catalogs
• [x] Limit visible catalogs to first 10 in config
• [x] Switch config.json to data dir
• [x] Add bright star catalog
• [x] Add Herschel 400

[brickbots]

@mrosseel I know we are closing in on an RC, but I really wanted to make good on a couple of catalogs that people have been after. With the ever expanding number, I thought I'd put some quick usability updates in:

• config.json moved to user data dir (makes re-ordering/selecting visible catalogs easier)
• Only the first 10 catalogs in the config are visible at all
• Catalogs can be selected as 'Active' (show up when cycling) via Catalog options page
• Added bright stars, and will add Herschel tomorrow