Convert HTTPLogClient to use libevent.

This removes the dependency on libcurl.
Add a wrapper for evhttp_request.

It's main function is to let you use a boost::function easily.
Test change.
Updating akamai branch of Certificate Transparency with all the changes need to run in the akamai setting.  Will probably no longer compile with just CT instructions.
Adding some test input files. Readme type information.  Modified scripts.
Add a config query table to reflect config message. It's more code then you would expect since I need to extract key/value pairs as strings from the protobuf message.  Now you can fields in the message and they'll just show up in the query table.  No extra code needed.
Merge branch 'akamai', remote branch 'origin/akamai' into akamai

Conflicts:
	cpp/Makefile
	cpp/log/akamai-query.cc
	cpp/log/akamai-query.h
	cpp/log/data_battery.cc
	cpp/log/data_battery.h
	cpp/server/ct-server.cc