Removed the "api_endpoint" setting from everywhere (in this repo)

[ttmc]

As described in issue #780, the api_endpoint setting isn't actually used anywhere (as far as I can tell), so I removed it from everywhere.

I added some docs to the page about the HTTP API to explain how the API Root URL is actually determined.

• Ran all unit tests. They passed.
• Ran flake8. It passed.
• Tested an AWS deployment. It worked.
• Played around with Docker based on edited Dockerfile. It seemed to work (but the bigchaindb load command seems to be broken now; that's another issue)

Resolves #780

[ttmc]

@sbellem Could you try out the Dockerfile and Docker Compose file to see if that stuff is still okay? I did some testing but I'm not a Docker pro.

I created a related issue to update the BigchainDB Python Driver (docs etc.): bigchaindb/bigchaindb-driver#142

[sohkai]

Oh interesting, we have BIGCHAINDB_SERVER_BIND that actually sets the server host and port. There's a lot of dockerfiles to go through and check in all the different repos, but since this env variable actually isn't used, nothing shouldn't be affected... right?

[ttmc]

BIGCHAINDB_SERVER_BIND isn't the whole story of how the public HTTP API URLs are determined. I added some documentation about how those are actually determined (in this PR, in docs/server/source/drivers-clients/http-client-server-api.rst).

[sohkai]

Just grepped through my local repos (which should include most of our docker-related files) and only found two instances of BIGCHAINDB_API_ENDPOINT (both depend on the python driver). Once we confirm that the driver doesn't need it, I'll remove those instances as well.

[vrde]

I did some manual testing and I was able to run configure, start, and show-config.

[codecov-io]

Current coverage is 96.64% (diff: 100%)

Merging #821 into master will not change coverage

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Powered by Codecov. Last update 97ff0ef...adde849

[ttmc]

This pull request can probably be merged around the same time as bigchaindb/bigchaindb-driver#171

[ttmc]

bigchaindb/bigchaindb-driver#171 was merged earlier today so I'm merging this pull request now. Farewell, "api_endpoint"