create identity for a given account - close #15

This MR lets a user create an identity using the "certify" button (first certification). It prepares the logic to handle other certifications (adding certification, renewing certification...) but do not handle these cases yet.

It also fixes type augmentation by:

• adding "skipLibCheck": true, to tsconfig.json (https://substrate.stackexchange.com/questions/4542/typescript-errors-when-using-polkadot-api/4570#comment11362_4570)
• changing the @duniter/interfaces to @polkadot/types/lookup
• adding imports to the generated files in src/interfaces/augment-*

I did not find a cleaner way to achieve this, but I can not imagine working with the duniter rpc api without proper type augmentation.