1. Add ale.setup and ale.setup.buffer for pure Lua configuration.
2. Update many global settings to use Booleans instead of numbers to
make types easiert to work with in Lua.
3. Radically reformat documentation and fix errors to make
documentation more usable for Neovim users.
It can be necessary to pass options to the puppet parser validation. The
most glaring example of this is when using Puppet 3, with the
`parser = future` option enabled. This update allows adding
`--parser=future` to the options passed to Puppet.
