Removed syntastic and replaced it with ale

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

sources_non_forked/ale/ale_linters/asciidoc/alex.vim

@@ -0,0 +1,11 @@
+" Author: Johannes Wienke <languitar@semipol.de>
+" Description: alex for asciidoc files
+
+call ale#linter#Define('help', {
+\   'name': 'alex',
+\   'executable': 'alex',
+\   'command': 'alex %s -t',
+\   'output_stream': 'stderr',
+\   'callback': 'ale#handlers#alex#Handle',
+\   'lint_file': 1,
+\})

sources_non_forked/ale/ale_linters/asciidoc/proselint.vim

@@ -0,0 +1,9 @@
+" Author: Daniel M. Capella https://github.com/polyzen
+" Description: proselint for AsciiDoc files
+
+call ale#linter#Define('asciidoc', {
+\   'name': 'proselint',
+\   'executable': 'proselint',
+\   'command': 'proselint %t',
+\   'callback': 'ale#handlers#unix#HandleAsWarning',
+\})

sources_non_forked/ale/ale_linters/asciidoc/redpen.vim

@@ -0,0 +1,9 @@
+" Author: rhysd https://rhysd.github.io
+" Description: Redpen, a proofreading tool (http://redpen.cc)
+
+call ale#linter#Define('asciidoc', {
+\   'name': 'redpen',
+\   'executable': 'redpen',
+\   'command': 'redpen -f asciidoc -r json %t',
+\   'callback': 'ale#handlers#redpen#HandleRedpenOutput',
+\})

sources_non_forked/ale/ale_linters/asciidoc/write-good.vim

@@ -0,0 +1,9 @@
+" Author: Sumner Evans <sumner.evans98@gmail.com>
+" Description: write-good for AsciiDoc files
+
+call ale#linter#Define('asciidoc', {
+\   'name': 'write-good',
+\   'executable_callback': 'ale#handlers#writegood#GetExecutable',
+\   'command_callback': 'ale#handlers#writegood#GetCommand',
+\   'callback': 'ale#handlers#writegood#Handle',
+\})