Modifying what args are passed into cpplint.py:

There are two changes:
1) With this change, cxx files are considered c++ files
2) In your .vimrc file, you can do: let g:cpplint_root=<root> to change
what the root directory is

This is going in my ~/.vimrc.local file:
" JonAWhite/vim-cpplint
" Use the current directory as the root directory for vim-cpplint
function! CpplintSetRoot()
  let g:cpplint_root = getcwd()
endfunction
nnoremap <F8> :call CpplintSetRoot()<CR>