ssdb v1.6.8.8 (new Formula)

Hi,

This is a new Formula for [ssdb](http://ssdb.io/?lang=en).
If there is any problem, please tell me know.

Thanks

ywjno

Can this test be modified to do something more substantial then e.g. `--version` or `--help`? See `cmake.rb` for an example of a formula with a good test. Thanks!