[#5][s]: remove obsolete tests.
[model][s]: various small-ish changes to model.

* add title attribute to issue
* change package_id to dataset_id on issue table
* tweak names of categories
[#9,#5,logic][m]: start work on a logic layer (issue create and show done) plus tests thereof.
[#9,#5,logic][s]: auth for show and create working.
[refactor][s]: remove old rest API as we will be providing action API going forward.
[controller][m]: refactor issue add to use logic system.

* Also put under test - see #9
* Also get rid of issue / issue category relationship for the present since we
  probably want something richer (like tags)
[fix][xs]: fix new issue link from issues page.
[#10,show][m]: basic issue show page working (with test).
[#11,comment][m]: issue comments in logic layer.
[model][s]: add status column to issue (open or closed).
[#11,comments][s]: new comment form on issue page.