Bumps version to 3.0.21
flakes
Bumps version to 3.0.19
Now depends on billiard 2.7.3.27
Bumps version to 3.0.17
Removes print statement
Bumps version to 3.0.15 and updates Changelog
Tests passing
Now depends on Kombu 2.5.4
Fixes typo in daemonizing tutorial. Closes celery#1055