Add support for CouchDB

[gabfssilva]

The communication with CouchDB is via HTTP. There is already a Java library called LightCouch (which looks great) that could be used by the connector, but:

• It uses blocking I/O, which we're trying to avoid for HTTP integrations (since it can be simple just reimplement)
• I'm planning how we could make some connectors multi-platform, including the HTTP module, so if we can skip using additional jars, I think we should go for it.

Anyway, just for consulting:

http://www.lightcouch.org/lightcouch-guide.html
https://docs.couchdb.org/en/stable/intro/api.html
https://camel.apache.org/components/3.20.x/couchdb-component.html