Load the private key only once.
Adding a thread pool class.
Simplify AsioRepeatedEvent into RepeatingCallback.
Enable Travis caching of APT packages.
Remove "using" statements from headers.
Fix a spacing mistake in thread_pool.{h,cc}.
Remove the unused Frontend::QueueEntry method.
Remove unused methods of CertSubmissionHandler.
Remove the experimental blob server.
Update link for Protocol Buffers project.

The Google Code page indicates they've moved to Github.
Use LogLookup instead of TreeSigner to get the STH.
Add a "get_roots" sub-command to client/ct.
Add the build status to the README.