Support pylama for python (#2266)

* Add pylama for python
* Consolidate python traceback handling

ale_linters/python/vulture.vim

@@ -46,19 +46,14 @@ endfunction
 
 
 function! ale_linters#python#vulture#Handle(buffer, lines) abort
-    for l:line in a:lines[:10]
-        if match(l:line, '^Traceback') >= 0
-            return [{
-            \   'lnum': 1,
-            \   'text': 'An exception was thrown. See :ALEDetail',
-            \   'detail': join(a:lines, "\n"),
-            \}]
-        endif
-    endfor
+    let l:output = ale#python#HandleTraceback(a:lines, 10)
+
+    if !empty(l:output)
+        return l:output
+    endif
 
     " Matches patterns line the following:
     let l:pattern = '\v^([a-zA-Z]?:?[^:]+):(\d+): (.*)$'
-    let l:output = []
     let l:dir = s:GetDir(a:buffer)
 
     for l:match in ale#util#GetMatches(a:lines, l:pattern)