Initial riak support
Add some documentation on class attributes

Also add handling of protocol.
Cleanup code related to connection to Riak

This is a leftover of previous work on this backend.
Switch default bucket name to celery
Add riak to extra requirements
Add Riak backend documentation
Fixed error in protocol handling for the riak backend
Use a heapq to avoid calling all entries for every iteration
Remove print
Support of missing CELERY_BIN and CELERY_APP, described in http://celery.readthedocs.org/en/latest/tutorials/daemonizing.html#id11
Added centos celerybeat init script + sysconfig example + simple tests
Adding self to CONTRIBUTORS.txt
Clarify behavior of rate limits in docs
Fixes duplicate nodename warning.  Closes #2046
Worker --detach default workdir is now CWD
Worker --detach with C_FAKEFORK no longer closes open fds.  Closes #2044
Did not log for Ignore and Reject
Events are now transient by default
Stupid zsh is messing with our beloved ksh heritage :chicken:

Closes #2038
Merge pull request #2037 from jonashaag/patch-1

Clarify behavior of rate limits in docs