Add support for a basic Travis continuous build.

Their environment is based on Ubuntu Precise, missing a number of necessary
packages, so this is only the subset that builds right off (Java and the
"pure Go").
Improve the Go binding for merkletree.
Run the Python tests on our continuous build.
WIP on DNS.
Add CXXFLAGS to the link phase.
Start of test harness.
Return leaf hash.
Temporarily include Eran's https://codereview.appspot.com/66940043/.
Also verify an inclusion proof for a leaf's hash.
Test work in progress.
Get rid of trailing whitespace.
Add missing file, move unmoved file.
Allow binary SCTs and logs on protocols other than HTTPS.
Remaining issues after a rebase.
Fix a couple of stray "https:"s.
Log responses.
Correct path.
Show error content.
Identify the type of the cert in the file name.
Calculate the right audit path length.