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.