Avoid overwriting NULL defaults by adding a check for non-null values in the HAR file during importing, esp. for cdn. Tweak expAge logic to base the expiration window on the requests start time (rather than $now).
Avoid overwriting NULL defaults by adding a check for non-null values in the HAR file during importing, esp. for cdn. Tweak expAge logic to base the expiration window on the requests start time (rather than $now).

git-svn-id: d5a8a4092b1c3eddbe100e0c5fc6446cfb12afd1@1064 fc7d47d3-c008-acd5-f51f-d19787b8a02f

HTTPArchive/httparchive,HTTPArchive/httparchive,paulcalvano/httparchive,paulcalvano/httparchive