change vcs function to use Zsh builtin

change vcs function to use Zsh builtin

  * The admone-git function is now called admone-vcs and uses Zsh's
    builtin VCS information system

  * Did some refactoring of the for loop in the set-prompt function
    to potentially speed it up a bit

  * Added software description to license file

  * Removed some unecesary config variables at the start of the file