replace exec with system()

- closes #64

autoload/vundle/scripts.vim

@@ -112,7 +112,7 @@ func! s:fetch_scripts(to)
 
   let l:vim_scripts_json = 'http://vim-scripts.org/api/scripts.json'
   if executable("curl")
-    silent exec '!curl --fail -s -o '.shellescape(a:to).' '.l:vim_scripts_json
+    let cmd = 'curl --fail -s -o '.shellescape(a:to).' '.l:vim_scripts_json
   elseif executable("wget")
     let temp = shellescape(tempname())
     let cmd = 'wget -q -O '.temp.' '.l:vim_scripts_json. ' && mv -f '.temp.' '.shellescape(a:to)
@@ -120,12 +120,13 @@ func! s:fetch_scripts(to)
       let cmd = substitute(cmd, 'mv -f ', 'mv /Y ') " change force flag
       let cmd = '"'.cmd.'"'                         " enclose in quotes so && joined cmds work
     end
-    silent exec '!'.cmd
   else
     echoerr 'Error curl or wget is not available!'
     return 1
   endif
 
+  call system(cmd)
+
   if (0 != v:shell_error)
     echoerr 'Error fetching scripts!'
     return v:shell_error