Improve row colouring for 'User Details' table on Page_Type=User (and others)

[gregcorbett]

Multiple information in the table is conditionally displayed, i.e.:

• Home Site if the viewed user has one
• Last Logged if the viewing user is an admin

See below screenshots

This makes it hard to colour the rows in this table manually, as is done currently.

vs

A fix exsits that chooses the row colouring dyamically and this should be applied to the 'User Details' table and others.

[gregcorbett]

I note the existence of #101, and while I think this issue this is a good first step towards #101, I think they should be tackled separately.