add modern theme

This is modern theme, as taken from Dropbox on 2013-07-24T1717+0100,
a version that shows up as last modified on 2013-07-05T1214+0100
TA8 & TA9 - Add styling for header, and config for logo change.

AG: This commit was originally authored by Dean Lennard on another repo.
I have migrated it to this repo which is properly rooted off of the
Moodle main repo.
TA8 & TA9 - Update code to work better

AG: I have migrated this commit by Dean Lennard from another repo
TA8 & TA9 - Styles & Image that failed to commit

AG: I have migrated this commit by Dean Lennard from another repo
TA8 - Add extra check if in a course with no logo set

AG: I have migrated this commit originally by Dean Lennard from another repo
TA11 - Fix attendance block issue.

AG: I have migrated this commit originally by Dean Lennard from another repo
TA-23 - Fix navigation

AG: I am migrating this commit originally by Dean Lennard from another repo