feat: encryption and decryption

[Dudleyneedham]

fixes https://github.com/KILTprotocol/ticket/issues/891

Adding functionality to encryption and decryption of the keys and credentials.

Changing to the redux store.
Changing to the services.

How to test:

Create a credential and keys to store.

Checklist:

• I have verified that the code works
• I have verified that the code is easy to understand
  • If not, I have left a well-balanced amount of inline comments
• I have left the code in a better state
• I have documented the changes (where applicable)

[Dudleyneedham]

Need to add - https://github.com/dchest/scrypt-async-js/ - in order to produce a key to access the local storage.

This is done with a plain text password and salt.

Storing the salt also in the local storage separate from the encrypted data.

First we check if the salt is in the local storage, if not generate a salt and store. Using the salt and password to create the key needed to encrypt and decrypt the local storage.

[tjwelde]