[dev] quark can not send files with '+' in the name

[Platon Ryzhikov]

Hi
I tried to use quark as local server for pacman but it returns 404 error for 
files with '+' in filename. I found the following lines in http.c (83-85):

if (*s == '+') {
        dest[i] = ' ';
}

Why does it replace '+' sign with space?