Bye opengraph_parser, hi open_graph_reader

opengraph_parser is basically unmainted, issues are ignored
or deliberately closed without fixing. It pollutes the global
namespace and has no verification of correctness.

The opengraph gem has basically the same issues, not really maintained,
unreleased patches on master since over a year, not really smart either.

So I created my own version and while at it, why not strive try to be
complete and robust, although it's still a work in progress.

This also improves general URL detection by parsing them
from the message after stripping markdown.

An additional dependency was added to support
fetching sites that require cookies to work at all.
For the same reason Faraday's default redirect limit was
bumped.

This is still sort of in beta state, so I left raising on, when the gem thinks the fetched object is invalid. Please watch your Sidekiqs and report those to https://github.com/jhass/open_graph_reader/issues (but make sure to search for the error message on the tracker first) :)