* Automatic dark/light colorschemes
A new `colorscheme` option is added with the capability to be always dark,
always light, or automatic based on the user's browser setting. This
makes the `inverted` option superfluous, and therefore deprecated.
Nomenclature of files, variables, etc are changed from `inverted` to
`dark` to reflect this change.
Closes#226.
* Remove inverted option completely
The `inverted` option is now not just deprecated, but removed
completely.
* add stackbit.yaml
* update field model for slug
* add config model
* update language config model
* update menu model
* katex should be a boolean value
* add labelField to menu item model
* math should be a boolean value
* Add 1-click create with stackbit button
John Schroeder
Robert Austin