2018-12-26, Version 10.15.0 'Dubnium' (LTS)

The 10.14.0 security release introduced some unexpected breakages on
the 10.x release line. This is a special release to fix a regression
in the HTTP binary upgrade response body and add a missing CLI flag
to adjust the max header size of the http parser.

Notable Changes:

* cli:
  - add --max-http-header-size flag (cjihrig)
    https://github.com/nodejs/node/pull/24811
* http:
  - add maxHeaderSize property (cjihrig)
    https://github.com/nodejs/node/pull/24860

PR-URL: https://github.com/nodejs/node/pull/25176