Added Crackboard support

[nafey]

• I'm the package's author and/or maintainer.
• I have have read the docs.
• I have tagged a release with a semver version number.
• My package repo has a description and a README describing what it's for and how to use it.
• My package doesn't add context menu entries. *
• My package doesn't add key bindings. **
• Any commands are available via the command palette.
• Preferences and keybindings (if any) are listed in the menu and the command palette, and open in split view.
• I use .gitattributes to exclude files from the package: images, test files, sublime-project/workspace.

My package is a client for supporting crackboard.dev which is a leaderboard for programmers. This allows Sublime Text users to compete on crackboard.dev leaderboard.

[packagecontrol-bot]

Automated testing result: WARNING

Repo link: Crackboard
Results help

Packages added:
  - Crackboard

Processing package "Crackboard"
  - WARNING: The package does not contain a top-level LICENSE file. A license helps users to contribute to the package.

[braver]

Some remarks:

• Access to the settings file should be possible via the package settings menu.
• Since this adds global event listeners, I would like to see users have some more control over when that runs. You want to be able to turn that off situationally or per project. The only way right now is to turn the package off or uninstall it, and reload ST. This could be as simple as an on/off boolean in the settings: such settings can be easily toggled using commands, keybindings, and even project settings.
• Calling the API on every text change might be a bit overkill for what crackboard needs. You might want to look into optimizing, or debouncing that.