Added query parameter to make the other query parameters 'sticky' by returning cookies that set them so are passed in subsequent requests.
Merge remote-tracking branch 'origin/trunk-tracking' into matterbury-sticky-options

if it merges an updated upstream into a topic branch.
Added system test for sticky options.
Moved cookie option tests to common test script.
Merge pull request #700 from pagespeed/matterbury-sticky-options

Added query parameter to make the other query parameters 'sticky' ...
options: support StaticAssetPrefix
Merge pull request #707 from pagespeed/jefftk-fix-static-asset-prefix

options: support StaticAssetPrefix