First version of What's New in MongoDB 2.4
edits: 2.4 overview pages and cross referencing
minor: cross referencing fixes
DOCS-1240 new package infrastructure
DOCS-1118: adding the cpp drier auth tutorial
wording of warning in agg

Signed-off-by: Sam Kleinman <samk@10gen.com>
removing references to 2.3 from release notes
edits: corrections to new packaging guides
copy edits to text-search
adding links to the release notes
minor: changing captialization
merge: copy edits
DOCS-641 geospatial final edits

Signed-off-by: Sam Kleinman <samk@10gen.com>
minor: edits