tweak date on HelloThere to match release date

This should help make the revision date more apparent, since HelloThere
is the first tiddler people see.
Merge pull request #16 from ericshulman/master

update default version # in setenv.bat for 2.8.0
Merge pull request #17 from ericshulman/master

content updates for TW280b1
Merge pull request #18 from ericshulman/master

added external JS build targets to main build script
TW280 test targets
Merge pull request #19 from ericshulman/master

update default version # in setenv.bat for 2.8.1