elixir-ls not picking up configuration from ale

## Information

**VIM version**

```
VIM - Vi IMproved 8.0 (2016 Sep 12, compiled Jun 05 2018 21:42:14)
Included patches: 1-1766
```

Operating System: Ubuntu 18.10

## What went wrong

I finally got elixir-ls and ale set up so that elixir-ls is an available linter, and a LS process is spawned. In an elixir buffer, I tried a number of :ALE... commands like GoToDefinition and Hover and they seem to do nothing. I introduced syntax errors and things that the compiler would warn about, but nothing shows up in the gutter.

I DO notice tiny CPU spikes in the LS process. There is no `.elixir_ls/` in my project. I have seen gutter signs from Ale in a ruby file.

### :ALEInfo

```
Current Filetype: elixir
Available Linters: ['credo', 'dialyxir', 'dogma', 'elixir-ls', 'mix']
Enabled Linters: ['elixir-ls']
Suggested Fixers:
'mix_format' - Apply mix format to a file.
'remove_trailing_lines' - Remove all blank lines at the end of a file.
'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
Linter Variables:

Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = v:null
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '%code: %%s'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 0
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'always'
let g:ale_linter_aliases = {}
let g:ale_linters = {'elixir': ['elixir-ls']}
let g:ale_linters_explicit = 0
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '%code: %%s'
let g:ale_lsp_root = {}
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_set_balloons = 0
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 0
let g:ale_sign_error = '>>'
let g:ale_sign_info = '--'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '>>'
let g:ale_sign_style_warning = '--'
let g:ale_sign_warning = '--'
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
Command History:

(executable check - success) /home/thomas/bin/elixir-ls/language_server.sh
(started) ['sh', '-c', '/home/thomas/bin/elixir-ls/language_server.sh']
```