[enh] overwrite secret_key from env with the SEARX_SECRET env var if exists - closes #845
[enh] overwrite secret_key from env with the SEARX_SECRET env var if exists - closes #845

dalf/searx,dalf/searx,jcherqui/searx,jcherqui/searx,jcherqui/searx,asciimoo/searx,asciimoo/searx,jcherqui/searx,dalf/searx,asciimoo/searx,dalf/searx,asciimoo/searx