Properties should be public

[fjcaetano]

Hi, this looks great, but I'm having trouble installing it with Cocoapods. The main issue is that the project seems to be missing access control.

I can see that currently, in master, the class and the style struct are public, but the properties are not. This means that we can't set them after init and we can't listen for value changes.

[TBXark]

Thanks to remind, now fix the bug