Github gist integration

[lauthieb]

Add the Github gist integration in Code Notes.
We will be able to retrieve, update, create and delete our snippets available on Github by passing a personal access token with the "gist" scope selected.

• Settings modal with github personal token
• Get all gists
• Display one gist on note card
• Display loading...
• Create gist
• Update gist
• Delete gist
• Tutorial to get personal access token