Some `ssl_ciphers` are now considered weak

[Takeno]

Some of the ssl_ciphers declared in default.ssl.conf.erb:22 are now considered WEAK.

Here is a screen from https://www.ssllabs.com

I don't know if dropping those ciphers will cause a breaking change. At least, I would like to have an ENV var to control a custom list of ssl_ciphers in case of more strict needs.

For now, we've replaced the entire default.ssl.conf.erb file.