Update neovim Python host prog path to /usr/local/bin/python2
Update neovim Python host prog path to /usr/local/bin/python2

After doing a `brew update` and cleanup today I started getting odd
Python-related errors when starting nvim.  Looks like the
/usr/local/bin/python symlink is going away moving forward.  Being more
specific in the g:python_host_prog variable to refer to python2
instead of just python fixes this issue.

kjhaber/dotfiles