make flash middleware implements countable
Merge remote-tracking branch 'lalop/flash_countable' into release-2.3.3
Bump version numbers
Bump version numbers
Add HHVM compatibility
Fix unit tests for HHVM
Remove vagrant files
Fix PrettyException middleware when custom log defined
Don't send any content when it's a HEAD request.
Add hhvm configuration example to README

Fix inline doc versions in a few class files
Fix README typo
Fix merge conflicts