Enable aes128-cbc and 3des old insecure ciphers support

[GAS85]

Enable aes128-cbc and 3des old insecure ciphers support

(cherry picked from commit 56b203a)

Issue:

Current implementation supports old CBC Ciphers, but I miss that they shall be explicitly enabled. If client force CBC ciphers use, there will be an nil pointer exception raised.

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x58c1a1]
goroutine 11361 [running]:
golang.org/x/crypto/ssh.newPacketCipher({{0x810724, 0x1, 0x1}, {0x810725, 0x1, 0x1}, {0x810726, 0x1, 0x1}}, {{0x30d8cafcc290, ...}, ...}, ...)
    /go/pkg/mod/golang.org/x/crypto@v0.1.0/ssh/transport.go:251 +0x1c1
golang.org/x/crypto/ssh.(*transport).prepareKeyChange(0x30d8cb0597a0, 0x30d8cb102400, 0x30d8cafe2400)
    /go/pkg/mod/golang.org/x/crypto@v0.1.0/ssh/transport.go:80 +0x126
golang.org/x/crypto/ssh.(*handshakeTransport).enterKeyExchange(0x30d8cb300000, {0x30d8cb30c280, 0x255, 0x255})
    /go/pkg/mod/golang.org/x/crypto@v0.1.0/ssh/handshake.go:623 +0x49a
golang.org/x/crypto/ssh.(*handshakeTransport).kexLoop(0x30d8cb300000)
    /go/pkg/mod/golang.org/x/crypto@v0.1.0/ssh/handshake.go:301 +0x166
created by golang.org/x/crypto/ssh.newServerTransport in goroutine 11231
    /go/pkg/mod/golang.org/x/crypto@v0.1.0/ssh/handshake.go:143 +0x136