Improve pubsub unittests
Update CONTRIBUTING.md
Update CONTRIBUTING.md
Add -json output mode for shell
Add expiration to events
Merge pull request #526 from theopolis/json-output

Add -json output mode for shell
Merge pull request #524 from theopolis/events_expiry

Events expiry
Replace linux cmdline tokens with spaces
Fix json results clear
Merge pull request #527 from theopolis/fix_linux_processes_cmdline

Replace linux cmdline tokens with spaces
Change exit(-1) to exit(EXIT_FAILURE)
Linux udev events
Clean before building CI
Merge pull request #529 from theopolis/linux_events_udev

Linux udev events
TARGETS updates
Fixing pidfile creation bug

If osqueryd was killed and another process was started with osqueryd's
old pid before a new osqueryd could start, osqueryd would encounter a
bug where osqueryd would never start.

This executes an osquery query to the processes table to make sure that
the name of the process is "osqueryd". Of course, you could perhaps
denial of service osqueryd this way, but that would require root
filesystem access (assuming that the last version of osqueryd was
ran as root). Thoughts?
Merge pull request #531 from facebook/pidfile-fix

Fixing pidfile creation bug