'Exclude' config is ignored

[patrickfav]

In your README it says

# List of files or directories to exclude
# e.g. custom or hand generated webp conversion files
exclude: []

but it seems it was never implemented:

jekyll-webp/lib/jekyll-webp/webpGenerator.rb

Line 64 in 22a08ec

# TODO: Do an exclude check

[sverrirs]

I haven't needed to use this feature. I'd be happy to review a PR if you have the time to implement this?

[patrickfav]

Alright, you just have to bear with me, ruby is not my strongest suite :)

[sverrirs]

No problem, I feel that a technically sound language agnostic solution is superior to any Ruby specific code. We can polish the rubyesque of the code together after ;)