Clivefile & cliver executable

[yaauie]

Create a Clivefile format & pair it with a cliver executable that executes the underlying command with a matching executable.

Example:

Cliver::Specification.new do
  add_dependency 'python', '~> 2.0', as: 'py2'
  add_dependency 'pygments', '~ >7.8', '>= 7.8.1'
end

Usage:
Locates appropriate executable, then replaces self process with it and all given arguments. Possible opportunity for Clivefile.lock file for optimization here, but you know, cache invalidation.

$ cliver pygments -i foo.txt -f