Rename the default config file to not be a hidden dotfile

[erkiesken]

It would be great if the default config file would not be a .svgo.yml hidden dotfile. Talking about this:

svgo/lib/svgo/config.js

Line 31 in 4822a44

defaults = EXTEND({}, yaml.safeLoad(FS.readFileSync(__dirname + '/../../.svgo.yml', 'utf8')));

This is causing issues with yarn (yarnpkg/yarn#1051) and in a roundabout way other modules, like extract-text-webpack-plugin (webpack-contrib/extract-text-webpack-plugin#352 (comment)).

[erkiesken]

Also was covered a bit in #622 without resolving it.

[GreLI]

Dotfiles for configs is a like common convention. I believe, yarn should work with such a files properly.

[TrySound]

v2 supports only svgo.config.js. No more hidden files.