Unchained Randomness

[jleni]

• [x] Extend configuration support
• [x] Modify internal handling / calculation
• [x] Adjust unit and integration tests
• [ ] Extend client side API

[emmanuelm41]

We extended the configuration to give support to unchained randomness here https://github.com/Zondax/drand/commit/2dd1727c9f472562e49ad385d4d0dc8c1a62a94a

[emmanuelm41]

We changed the internal calculation based on the configuration here https://github.com/Zondax/drand/commit/0243d7cfc904fd2b3e9e5d8dba02ebc11be6f28f

[emmanuelm41]

We extended and ajust the tests here https://github.com/Zondax/drand/commit/86c83d1134e79bd3e1df8facb074413a25dcada2. There are a lot of other commits to fix some issues with the tests.