FIX: build http for cross compiles.
FIX: build http for cross compiles.
REFACTOR: revise default log message format

Cleanup some old trace.
Change mprSetLogHandler to return the prior log handler.
REFACTOR: change httpTrace to take a string event.
REFACTOR: Use HttpConn.reqData in dirHandler.
CLEAN: Revise log messages.
DOC: update security doc
REAFCTOR: continue httpTrace refactor