Reconsider dependency to zxcvbn due to its size

[glepretre]

Looking for something in the built file formol.js I noticed a huge word list.

This is coming from our dependency zxcvbn to estimate password strength.

While there are reasons behind it:

• https://github.com/dropbox/zxcvbn/issues/169
• https://www.usenix.org/conference/usenixsecurity16/technical-sessions/presentation/wheeler
• https://github.com/dropbox/zxcvbn/issues/59

We might reconsider this dependency as its size is 823 kB, upon a total of 1.5 MB of the formol.js file.