Remove selector restriction when creating group

[ockam]

Removing the img selector restriction allows to use v-img on other elements. As in:

<div v-img="{group: 'myGroup', src: 'path/to/image.jpg'}"></div>

This could resolve #27.

Not sure if this can have side effects on the rest of the library, but it works fine for me.

[ockam]

Oups. Just noticed I reproduced PR #42... 🤷‍♂️

[fahrenq]

Hi @ockam!

Than you very much anyway!

Sorry, don't have time yet to resolve all issues and PRs, I'll come and continue working on the plugin shortly :)

Thanks!

[simonbrunel]

@fahrenq it looks like this PR is much easier to review than #42 since it focuses on removing the <img> restriction (1 line change). Do you need anything else to be able to review, merge and release these changes? Can we help in any way?