Switch to modern bcrypt implementation

[Leont]

This module is currently using Crypt::Eksblowfish::Bcrypt which is essentially unmaintained for the past decade. In particular, the rest of the world upgraded to the 2b variety of bcrypt back in 2014.

I've recently released Crypt::Bcrypt, which does support modern varieties of bcrypt. Or you could go a step further and use Crypt::Passphrase and gain cipher flexibility.

[Leont]

Actually, there's another problem that kind of complicates fixing this: the code is currently not saving/using the cost parameter, which means it can't scale up together with Moore's law (the security decreases every year because computers get faster).