Update settings editor to use sqlite3

[tomlin7]

Fixes #451

Add functionality to update config manager state and store settings using sqlite3 in the settings editor.

• Add methods to save and load settings from sqlite3 db
• Update add_sections method to load settings from the config manager.
• Update Settings to use sqlite3 for configuration.
• Update late_setup method to load settings from sqlite3.

[vyshnav-vinod]

Hey i was just going through this PR and noticed that you are using key value in sqlite. Maybe this would be helpful? https://github.com/piskvorky/sqlitedict

[tomlin7]

@vyshnav-vinod oh that's very cool! thanks for sharing, will check when I get back to this PR <3