Add section about JCM memory settings
Add documentation for password provider changes to support salting

This commit modifies the sysadmin and developer documentation to document
the latest changes to the password provider including pasword salting support.
Rewrite optimization lines to include quotes as tested in the job
Try to improve the sentence about reverting salting
Minor fixes to the server upgrade page

Conflicts:
	omero/sysadmins/server-upgrade.txt
Fix dot in password provider page
Add note to What's new page about password salting

Conflicts:
	omero/sysadmins/whatsnew.txt
Fix salting version introduction
Merge pull request #994 from sbesson/salt_dev44

Add documentation for salting in 4.4.12