Doc update for changes to course outline

For STUD-1034
Added file pagination info

For files & uploads page.  stud-1034
Updated topic Testing Your Course for new outline page

Updated some text and all new images
Subsection grading changed

Changed terminology to not refer to setting grading policy for a
subsection, but selecting an assignment type
Find Files doc update

clarified sentence on what's shown at top of page
Updated change log

Added new changes in Mistletoe sprint to change log.
Moved change log

Moved change log to beginning of document.
added SPOC info

For stud-1019
Merge pull request #2100 from edx/markhoeber/documentation/stud-1034

Updates for 1-7-2014 release changes in Studio -- Outline and Files pages