Integration with Ethereum for registering DID -> HASH mappings

[Exulansis]

Description

We are currently intending to store the DDOs on IPFS by default. Since the documents are content addressed, we need a dynamic mapping that can be updated with the new hash whenever the documents change. Some more information can be found in #13.

For now a basic implementation in form of an Ethereum smart contract will be built.

TODO:

• Implement the functions for registering and reading the DID hash.
• Implement corresponding tests.

A slightly better test setup is needed, at the moment we need to run test rpc and deploy the contract manually, this will be optimized.

• Research and set up Infura.

[Exulansis]

The contract currently resides under this repository.

[Exulansis]

The TypeScript wrapper has been moved to the appropriate aforementioned repository. This allows for better separation of concerns and easier testing.
This branch will be re-purposed. It will track the integration of the mentioned module.