Make Zubat theme tabs more readable

[nblackburn]

The Zubat theme tabs need tweaking to be more readable as it's hard to make them out.

https://github.com/klauscfhq/hyper-pokemon/blob/master/pokemon.yml#L292-L297

[klaudiosinani]

It is possible to manually change the tabs color through the pokemonSyntax option, by setting it to dark, thus achieving a better contrast. This is something that will happen automatically on the upcoming release.

// ~/.hyper.js
pokemon: 'zubat',
pokemonSyntax: 'dark', // Defines the color of the terminal tabs    

[klaudiosinani]

Fixed on 19311b5.