background_process 6.x-1.8

NOTE: Please clear cache before running update.php

Bugfixes:
* #1345262: background_process_update_7001() is broken
* #1354582: Strict warning: Creating default object from empty value in background_process_http_request()
* Don't accept gzip encodings for background requests.
* Fixed service host determination when starting a background process

Improvements:
* Reuse more code
* Updated to coding standards

New features:
* #1347688: Making ETA message optional, Deleting used variables on uninstall
* API for issuing http requests a'la HTTPRL (Plans to join forces or depend on HTTPRL are in place).
* SSL
* HTTP Basic Authentication
* "Rolling window" for asynchronous http requests.
* Determine default service host