Luminoso-api

* Added a new method, `wait_for_sentiment_build`, to allow users to wait for
the new document-level sentiment build to finish instead of waiting for
the main build process (which happens first). `wait_for_build` remains as
a method for users who want to know when non-sentiment API endpoints become
ready to use.

* Added a new timeout optional parameter to the v5 client to be able to pass
it the the underlying requests object. Without setting it the request can
hang forever if the server does not respond in a timely fashion. In case of
a timeout the request will now return a LuminosoTimeoutError.

* Changed the default client from the v4 client to the v5 client, as well as
correspondingly swapping the README files to make the v5 client's README
the main one.

* Removed functionality from the v4 client specific to science endpoints
(that is, any URL starting with "projects"), including:

- The logic for setting the client's URL to the user's default account on
login
- The "upload" method for uploading documents to a project
- The "wait_for" method for waiting for a project to build

* Removed "documentation" method from v4 client. This had been designed to
download a text version of the API documentation, but for some time the API
has been returning the documentation only as HTML.

* Updated the default URLs, and URLs in documentation, to the new
"daylight.luminoso.com". Also added code in token authentication in both
v4 and v5 clients to look for tokens for a domain with "analytics" in it
if a domain with "daylight" was specified but no token was found, to help
users transition to the new URLs.

* Added a custom "user-agent" to the v5 client's headers, along with
functionality to allow users (and specifically the CLI scripts) to add a
suffix to the user-agent

* Added connect_with_username_and_password() to the v5 client to ease the
transition from v4 to v5.

* Client changes

- The commands `lumi-upload` and `lumi-download` now use the v5 API.
You can upload a JSON-lines file (a file in which each line is a JSON
document) as a Luminoso v5 project, and download the resulting project
in the same form.

* Small documentation fixes

* Added change_path() to the v5 client as a deprecated alias for
client_for_path(), analogous to the upload() alias.

* Minor change to turn the README.md into the documentation that appears on
PyPI.

* Client overhaul to interface with the v5 API.

- A client for the v4 API is still available, and is the default client,
but there is a sunset period for the v4 API.