Minor edit of 7.8.8 version history item.
===GT=== #3510
Merge branch 'V7_8_8-branch' into V7_8-branch
Have V7_8-branch manual announce itself for version 7.8.9.
Set 7.8.8 release date of March 28, 2013.
Merge branch 'V7_8_8-branch' into V7_8-branch
Merge branch 'V7_8-branch' into V7_9_5-branch

Conflicts:
	doc/condor-macros.tex