Removed syntastic and replaced it with ale

Read more here:
https://github.com/w0rp/ale

sources_non_forked/ale/ale_linters/fountain/proselint.vim

@@ -0,0 +1,9 @@
+" Author: Jansen Mitchell https://github.com/JansenMitchell
+" Description: proselint for Fountain files
+
+call ale#linter#Define('fountain', {
+\    'name': 'proselint',
+\    'executable': 'proselint',
+\    'command': 'proselint %t',
+\    'callback': 'ale#handlers#unix#HandleAsWarning',
+\})