Implements references in the issue model

[discorick]

Adds:

• accept(vistor) to the base client side model
• Uses the IssueReferencesVisitor to discover issues based on references found in the body (asynchronously)

Discussion point, how much should we hydrate issues that are closed and not on the board? Currently I am returning the reference, with a state i.e

{
  url: 'https://huboard.com/huboard/huboard/issues/1'
  id: 12345,
  text: '#1'.
  state: 'closed'
}

Discovered issue references that already exist in memory are returned by their in memory counterparts (a full issue model).

related to huboard/huboard#666

[dahlbyk]

This is looking pretty good, but I don't think references from a linked board back to the parent board are working (e.g. https://huboard-rails-pr-309.herokuapp.com/huboard/huboard#/issues/104311313).

[discorick]

@dahlbyk How did you determine that? (it wont be in the payload of the issue details)

[dahlbyk]

How did you determine that? (it wont be in the payload of the issue details)

I set a breakpoint somewhere in the visitor, probably in discoverClosedIssue.

[discorick]

This is looking pretty good, but I don't think references from a linked board back to the parent board are working (e.g. https://huboard-rails-pr-309.herokuapp.com/huboard/huboard#/issues/104311313).

@dahlbyk got it here: aa0363d