(no default getCurrentTime anymore)

This is a first stepping stone in avoiding bugs by having `UserId` and
`ContextId` being proper types, and not synonyms.

We also refactor things to have `AuthenticatedUser` carry the `UserId`.

Basically, Gargantext.Prelude exports all of Protolude now.

This commit refactors the codebase to add a new function called
`addDocumentsToHyperCorpus` which generalises the common pattern of
calling `insertMasterDocs` and later adding the documents via the DB
`Doc` functions.

It also "lowers" some functions to run into a plain `DBCmd`.

Also, use ISO639 languages in some places.

This big commit improves the jobs API in a way that now we can
completely abstract away over a JobLog.

We don't need the IO monad there, just added a default date for
Duckling to make the parser.