Refactor global variables into script local variables.

These variables only occur in one file each.  By making them script local
variables this is "documented" in the code.  At the same time the global
namespace is polluted less.

Changed:
    g:bundle_names          -> s:bundle_names
    g:vundle_last_status    -> s:last_status
    g:vundle_log_file       -> s:log_file
    g:vundle_view           -> s:view

autoload/vundle/installer.vim

@@ -55,11 +55,11 @@ func! s:process(bang, cmd)
 
     exec ':norm '.a:cmd
 
-    if 'error' == g:vundle_last_status
+    if 'error' == s:last_status
       let msg = 'With errors; press l to view log'
     endif
 
-    if 'updated' == g:vundle_last_status && empty(msg)
+    if 'updated' == s:last_status && empty(msg)
       let msg = 'Plugins updated; press u to view changelog'
     endif
 
@@ -118,7 +118,7 @@ func! vundle#installer#run(func_name, name, ...) abort
     throw 'whoops, unknown status:'.status
   endif
 
-  let g:vundle_last_status = status
+  let s:last_status = status
 
   return status
 endf