Merge pull request #11 from DamienSeguin/master

Synchronously create the dest directory
Updated execSync (causing issues)
Version bump
Asynchronous rewrite, resolves #7, resolves #12
Fixes and cleanup
Create all favicon files, resolves #3
Version bump
Proper testing and errors, fixed html bug
Metadata fix
Fixed manifest error throwing
Fixed empty manifest data bug
Added new iOS and Android icon sizes
Disable white icon conversion by default
Added OpenGraph function
Multi-source option, fixed async Firefox manifest
Updated readme
Further readme fixes
Document appropriate source image sizes
Fixed manifest writing issue
Fixed file paths on HTML