HPCC-10292 ZIP from Zap has path info

Currently when zipping logfiles, paths are included as part of the zip, so
you have something like

//10.0.2.15/var/log/HPCCSystems/myeclagent/eclagent.2013_10_15.log

This effectively hides the file in some ZIP browsers, so we should strip
out the paths and just save the filename

Signed-off-by: William Whitehead <william.whitehead@lexisnexis.com>
Merge pull request #5064 from RussWhitehead/zapFix_4.2.0

HPCC-10292 ZIP from Zap has path info

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>