[MAR-39] Allow encrypted export

[cfu288]

Allow user to export data as a blob or zip file.

Need to decide on how to best encrypt. AES 256 with PBKDF2? bcrypt, scrypt, Argon2

Research

PBKDF2 as a symmetric key

Another popular way PBKDF2 is used is as a means of turning a user supplied password into a symmetric key suitable for use with the AES algorithm. This relies on the fact that AES can use anby value as its input that meets certain length and entropy requirements and that PBKDF2 can produce a hash of any length which meets those requirements for entropy.

_{From SyncLinear.com | MAR-39}