Option to generate mapping of icon id to hex codes

[bmingles]

fantasticon currently generates an icon.json file containing mappings of icon id to decimal codes. It would be nice to be able to generate one with hex codes as well for consumers that need an easy mapping without having to do the conversion.

[equinusocio]

This is a must. We need a way to look/serach codepoints as hex in order to use them manually inside css or in other files. I tried creating a custom json template but doesn't seem to work.