Add upgrade step for mail control panel. Refs PLIP 10359.
add plone.app.jquery, which dropped out as plone core dependency in 5.0
include plone.app.jquery configuration for 4.2 upgrade steps
Merge pull request #20 from plone/plip10359-mail-controlpanel

Add upgrade step for mail control panel. Refs PLIP 10359.
add upgrade step to copy security panel settings into the registry