Add the Reek checker for Ruby. (#490)

Add the Reek checker for Ruby.

ale_linters/ruby/reek.vim

@@ -0,0 +1,53 @@
+" Author: Eddie Lebow https://github.com/elebow
+" Description: Reek, a code smell detector for Ruby files
+
+let g:ale_ruby_reek_show_context =
+\   get(g:, 'ale_ruby_reek_show_context', 0)
+
+let g:ale_ruby_reek_show_wiki_link =
+\   get(g:, 'ale_ruby_reek_show_wiki_link', 0)
+
+function! ale_linters#ruby#reek#Handle(buffer, lines) abort
+    if len(a:lines) == 0
+        return []
+    endif
+
+    let l:errors = json_decode(a:lines[0])
+
+    let l:output = []
+
+    for l:error in l:errors
+        for l:location in l:error.lines
+            call add(l:output, {
+            \    'lnum': l:location,
+            \    'type': 'W',
+            \    'text': s:BuildText(a:buffer, l:error),
+            \})
+        endfor
+    endfor
+
+    return l:output
+endfunction
+
+function! s:BuildText(buffer, error) abort
+    let l:text = a:error.smell_type . ':'
+
+    if ale#Var(a:buffer, 'ruby_reek_show_context')
+        let l:text .= ' ' . a:error.context
+    endif
+
+    let l:text .= ' ' . a:error.message
+
+    if ale#Var(a:buffer, 'ruby_reek_show_wiki_link')
+        let l:text .= ' [' . a:error.wiki_link . ']'
+    endif
+
+    return l:text
+endfunction
+
+call ale#linter#Define('ruby', {
+\    'name': 'reek',
+\    'executable': 'reek',
+\    'command': 'reek -f json --no-progress --no-color',
+\    'callback': 'ale_linters#ruby#reek#Handle',
+\})