Add a hashtag before color codes

[Konstantin Pschera]

Instead of:

"common": {
  "bg": "0F1419",
  "fg": "E6E1CF",
  "accent": "F29718"
}

we should export this:

"common": {
  "bg": "#0F1419",
  "fg": "#E6E1CF",
  "accent": "#F29718"
}

Thoughts?