Log metric that produced exception

To help diagnose issues such as those reported in
graphite-project/graphite-web#282

Backport from 80d111f8a270c5272089c280366f44a36d905eb4 on master branch.
Adding the ability to reorder metrics via the composer

This adds a new button menu on the right panel and new menu to the target context menu.
Gives the ability to select X targets, and move them in unison up and down.
If you select exactly 2 targets, then you can also do an in place swap.
Fix issue #617: handle TIME_ZONE=None

Fortunately Django is kind enough to give us
a method to get the current timezone, there
is no need to access settings.TIME_ZONE
directly.
Merge pull request #618 from jcsp/fix-none-timezone

Fix issue #617: handle TIME_ZONE=None
Merge pull request #503 from justino/sortable_metrics_0.9.x

Adding the ability to reorder metrics via the composer
Merge pull request #446 from jamesjuran/carbonlink_exception_backport

Backport to 0.9.x: Log metric that produced exception