Livebridge-liveblog

This version adds the capability of filtering the posts forwarded from a Liveblog source. Please see the README.md for details.

* Upgraded livebridge dependency
* Added requirements-dev.txt
* Fix for aiohttp session.close()

* Every Liveblog is checked every 10 minutes (default) in the background for status change. (**open/closed**)
* Archived (closed) blogs are not being polled for new postings.
* Added **source_check_interval** to config options.
* Added **verify_ssl** to config options. SSL verification check controllable through config.
* Fixing lb_highlight for Liveblog 3.3+

* added liveblog target, still experimental
* upgrade dependencies