Addition of assessment docs, URL changes for help/etc

General formatting of assessment docs adjusted.
Moved to Marking Poles to assessment.xls, along with simplified
instructions.
Added Lesson Plan 2 sheet, as we ask for two lesson plans.
Toned down the colours in the example table in
Assessment-Instructions.pdf.

Changed URLs for help to point to http://www.one-education.org/academy
(which will come to life in the next day or two)
Merge pull request #32 from cottonpaul/master

Addition of assessment docs, URL changes for help/etc