Merge pull request #499 from hflynn/11093-develop

Database backup warning
Resizing images for pdf only
Merge pull request #501 from hflynn/rebased/develop/pdf-images

Pdf images resizing (rebased onto develop)
Add/remove missing/incorrect Annotation types
Fix formatting and typos in existing doc
Add missing close parenthesis
Corrected StructuredAnnotations hierarchy
Add seealso markup linking to the SA generated schema documentation
Reference latest schema 2013-06
Added MapAnnotation

See https://github.com/openmicroscopy/ome-documentation/pull/496#issuecomment-25439727
merge develop -D org -I include -E exclude: PR 450 (omero: Python 2.6 is the minimum supported version)
merge develop -D org -I include -E exclude: PR 502 (Fix list of Annotations (rebased onto develop))