Upgrade meek to 0.16
The reason for this upgrade is legacy/trac#15427 (moved), which fixes bridge lines that are missing the "front" parameter, such as those in the How to set up meek on a cooperating web server post.
Here is the diff since 0.15. https://gitweb.torproject.org/pluggable-transports/meek.git/diff/?id=0.16&id2=0.15