Improve solarized color names

Rationale: Solarized has color-names that are able to be referenced on the solarized website, and are used in other colorschemes. Since these are 'established' it's probably best to respect the defined names and use those, making current and future colorschemes easier to build/understand.

colors.json
* Left the old color-names in colors.json for backwards compatibility
* Added the established solarized color-names

solarized.json
* Updated the solarized colorscheme in vim to the new names