#58 module manager support

Major Refactorings and preparation for Module Manager and Github Mods
- Replace "Executors" with "Workflows"
  - Far more flexible and concise
  - can be run by any executor
  - Support executing multiple queued tasks
- Begin support for synchronising Downloaded Files that are not mods
- Mod Pages are no longer curse-exclusive
  - But so far, only curse is supported
- Begin support for Module Manager
  - Scraping of Jenkins Site
  - Begin GUI for updating Module Manager