Bug 1027739: Adjustments to allow tagged post blocks to be copied

Note unlike copying journal blocks there is a special option for
taggedposts block that allows for copying of tags only.

This means copying the tags used in the block across to the new block
instance only.

So if you copy your own page the new taggedposts block should display
the same content as the old one

If you are another user it should display either nothing or the
journals you have with the same tags

Change-Id: I8011919dcf4e24e643bc2b07b1ba87db0963b81f
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>