Currently does
- upgrade: change resumeinterest / resumecoverletter embedded items to
use value that matches their artefacttype value
- upgrade: resave resume blocks for those people that have something
embedded

- on saving a resumefield / entire resume block it works out what
embedded items are associated and adds them to view_artefact table
- on saving resume item (including composite resume item) it works out
what embedded / attached items are associated and if there are resume
blocks owned by the user it updates the view_artefact rows too
- added an EmbeddedImage::has_embedded_image() function that checks
html markup and returns true/false if the markup contains an embedded
image

Change-Id: I1db7eea54e87477aba3f1c2a84434544af8fee51
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>