Fix #257 in preparation for #427, standardise options with fallbacks, and make it so every value can be computed dynamically

ale_linters/elm/make.vim

@@ -62,4 +62,3 @@ call ale#linter#Define('elm', {
 \    'command_callback': 'ale_linters#elm#make#GetCommand',
 \    'callback': 'ale_linters#elm#make#Handle'
 \})
-