Fix #260 automatically set .csslintrc files from ancestor directories

ale_linters/css/csslint.vim

@@ -1,9 +1,18 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: This file adds support for checking CSS code with csslint.
 
+function! ale_linters#css#csslint#GetCommand(buffer) abort
+    let l:csslintrc = ale#util#FindNearestFile(a:buffer, '.csslintrc')
+    let l:config_option = !empty(l:csslintrc)
+    \   ? '--config=' . fnameescape(l:csslintrc)
+    \   : ''
+
+    return 'csslint --format=compact ' . l:config_option . ' %t'
+endfunction
+
 call ale#linter#Define('css', {
 \   'name': 'csslint',
 \   'executable': 'csslint',
-\   'command': 'csslint --format=compact %t',
+\   'command_callback': 'ale_linters#css#csslint#GetCommand',
 \   'callback': 'ale#handlers#HandleCSSLintFormat',
 \})