add a pre-requisite check function with check for com.ginkgostreet.multiform; Hide usual help text, provide a user Status message;
incorporate code-review feedback
move dependency check to Upgrader class
Replaced magic number with extension manager status constant.
Fixed typo in name of required extension. Hyperlinked extension URL. Added fatal error for unknown error keys.
Reworked language for missing prereq error message. Changed message to display in a popup instead of in the old message space.
Moved the post-install/upgrade prereq checks further up the stack.
Added user feedback to upgrade script.
Restored accidentally deleted call to parent method.
Merge pull request #1 from GinkgoFJG/ginkgomzd-VOL-59

Patch to VOL-59
Merge pull request #193 from ginkgomzd/VOL-59

Vol-59 Declare dependency on com.ginkgostreet.multiform