Support camelCase key

[mrleblanc101]

Hi,
I don't really like having hyphenated key in my nuxt.config.json.
Would it be possible to add support for camelCase key too ?

- 'google-gtag': {
+ googleGtag: {
    id: 'UA-some-id',
},

[mrleblanc101]

I see in the code that this is supposed to be supported.
But it was never released to npm, the latest version is 1.0.4 and the commit adding this feature was release after.