Removed syntastic and replaced it with ale

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

sources_non_forked/ale/ale_linters/ruby/ruby.vim

@@ -0,0 +1,22 @@
+" Author: Brandon Roehl - https://github.com/BrandonRoehl
+" Description: Ruby MRI for Ruby files
+
+call ale#Set('ruby_ruby_executable', 'ruby')
+
+function! ale_linters#ruby#ruby#GetExecutable(buffer) abort
+    return ale#Var(a:buffer, 'ruby_ruby_executable')
+endfunction
+
+function! ale_linters#ruby#ruby#GetCommand(buffer) abort
+    let l:executable = ale_linters#ruby#ruby#GetExecutable(a:buffer)
+
+    return ale#Escape(l:executable) . ' -w -c -T1 %t'
+endfunction
+
+call ale#linter#Define('ruby', {
+\   'name': 'ruby',
+\   'executable_callback': 'ale_linters#ruby#ruby#GetExecutable',
+\   'command_callback': 'ale_linters#ruby#ruby#GetCommand',
+\   'output_stream': 'stderr',
+\   'callback': 'ale#handlers#ruby#HandleSyntaxErrors',
+\})