Add a test to make sure we have links
Remove the old vmethod implementation
Filter the change lines in the model

Also escape HTML there, since we need to preserve the links when we move
to the template. html filter stolen from Template::Alloy.

The design of this code isn't the pretties, but it does something for
now.
We should have a number for RT links
Add Github linking support

This will most likely need refinement over time.

One idea could be to support the extended syntax that github markdown supports

* <user>/<repo>#<num> links to the bug in that repos issues
* <repo>#<num> links to the bug in same user, different repo
remove Data::Dump
Add tests for _gh and _rt_cpan regexes

The tests are maybe crude, but they document some of the patterns we match, and
allows us to add more as there will be more discovered
Merge pull request #907 from omega/omega/refactor-rt-linker

refactor rt linker, add GH issues support