Merge branch 'master', remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'origin/master' into log-to-console
Revert "Print, and log, messages in command-line utilities."
Fixed various tests.
Tests no longer run automatically when imported.
aggregate_tests now loads all the unit tests into one suite and runs them together,
so that any failures and errors show up together in a concise report.
Minor changes following review
Remove test print statements
Merge branch 'master' into path_hash_prefix
Improved checking of the "paths" and "path_hash_prefix" attributes.

Removed checking whether "path_hash_prefix" is consistent with the
delegated paths in the delegator, because now the delegated paths may
list directories instead of simply files.
Bugfix.
Remove list.sort() and cleanup try-except blocks in signercli.py

Previously, _make_delegated_metadata() attempted to minimize the number of target directories in the "paths" field
of delegations by calculating common root-most directories.  This bahavior was found to be unsafe and removed, and as a result,
the sort of delegated targets is no longer needed.
Update updater.py to retrieve compressed versions of Targets metadata

This change addresses issue #85.  The previous implementation only recognized compressed versions of "release.txt".
Preliminary update preceding the major path_hash_prefix changes

This update addresses issue #86.  It begins by removing the wholesale downloading of all targets metadata and only downloads & verifies the metadata for the roles it only needs; the "lazy walk" scheme.
Merge branch 'master' into path_hash_prefix
Update updater.py to also check for compressed versions of targets.txt

Also added a comment to make it obvious that referenced_metadata should always be release for delegated roles.
Fix some bugs with tests.
Fix bugs with a library and a few unit tests.

Include a missing import for a library so that it does not throw a
runtime error.

Include missing imports for unit tests so that they are standalone.
Merge remote-tracking branch 'origin/master'
Merge branch 'master' into path_hash_prefix
Merge remote-tracking branch 'upstream/master'