Added code completion for rust

ale.vim

@@ -2,13 +2,18 @@
 " Install the flake8, python-pylint packages
 let g:ale_linters = {
     \ 'python': ['flake8', 'pylint'],
+    \ 'rust': ['rls'],
     \}
 
 let g:ale_fixers = { 
     \ 'python': ['yapf'],
+    \ 'rust': ['rustfmt']
     \}
 
 nmap <F10> :ALEFix<CR>
 
-let g:ale_fix_on_save = 1
+let g:ale_rust_rls_toolchain = 'nightly-YYYY-MM-DD'
+
+let g:ale_fix_on_save = 1
+let g:airline#extensions#ale#enabled = 1