SERVER-7172 Field checker now checks for empty fields as well.
SERVER-7172 Allow init() to be called more than once in field parsing (for reuse).
SERVER-7174 Renamed the mods common interface and its calls to be simpler.
SERVER-7174 $set update mod built over the new mods framework.
SERVER-6400: MatchExpression version of Matcher code complete.
SERVER-9578 install mongos signal handler for SIGUSR1 before spawning any threads
Removed executable bit from README