Adding issue history tabs plugin

This plugin splits the issue history into two tabs, 'all' and
'comments'. The comments tab only displays the issues notes and all
displays everything (it defaults to comments).
I think this will make it easier to navigate the issue page, as some
issues' histories can can very large.
Fixed grouping issues by devices

Some dodgy sorting was screwing up how the issues were being grouped.
This is now fixed.
Removed group by devices

Grouping by device is too much of a hassle, as there is no uniquely
human readable field for each device so I'm removing it.
Removing cinema/devices sorting entirely

We were seeing a strange SQL bug when sorting by cinema or device and so
for this release we're just going to comment this stuff out.
Changed default tab on issue history

Now tab only defaults to comments (as opposed to all) when there are
more than 25 entries in the issue history.
Merge pull request #73 from dannybutler/group_by_devices_fix

Fixed grouping issues by devices
Make a record of deleted issues so they can be deleted from Producer too, when the sync task runs. NB: db migration required.
Template the sync of deleted issues, but waiting on Producer to complete.
Hide concept of replying to a kb article.
Merge pull request #75 from blrnw3/kb-changes

Hide concept of replying to a kb article.
Routes patch fix
Merge pull request #76 from blrnw3/master

Routes patch fix
Merge pull request #69 from dannybutler/issue_history_tabs

Adding issue history tabs plugin
Fixed accidental commenting-out.
Merge pull request #74 from blrnw3/producer-more

Make a record of deleted issues so they can be deleted from Producer too...
Merge branch 'master' of https://github.com/artsalliancemedia/redmine into fix-docs