add log_logstash plugin to emit logstash json_event messages.
import thresholds from thresholds.c
Merge branch 'feature-riemann-threshold' of github.com:pyr/collectd into feature-riemann-threshold
Add threshold checks for riemann output.
Merge branch 'feature-log-logstash' of github.com:pyr/collectd into feature-log-logstash

Conflicts:
	configure.ac
disk: Add udev-based device renaming on Linux

On systems with large collections of allocated disk resources, the
kernel provided names can be difficult to use to logically group or
compare collected values.  To grant users the ability to assign custom
instance names for disk devices, collectd can query for a specified udev
attribute.  If the attribute is present, its value is subsituted for the
kernel name when submitting the data points.
increased buffer size
Syslog: if we can't find the loglevel specified by the configuration string default to 'info' and warn about the unknown configuration option. no way to make syslog totaly silent anymore.
CPU Percentage: after realloc the pointer becomes invalid; need to work on new pointer.

fixes https://gist.github.com/toni-moreno/a2f80021535f87202de7
Add support for durable AMQP queues

The collectd amqp plugin allows setting messages as persistent but is hardcoded to create or use transient queues that are set to auto_delete.  This commit adds support for QueueDurable and QueueAutoDelete boolean values in the config file and changes the queue creation as appropriate.

If the values are not set in the config file, QueueDurable defaults to false and QueueAutoDelete defaults to true.

Tested with RabbitMQ 3.3.1
Merge pull request #636 from dothebart/config_debug_nonsilent

Syslog: don't go all silent on 'debug' with production binary
add brackets to the list of characters graphite chokes on

(cherry-pick of 109cc80a to avoid a merge conflict later on)
mention new options to cpu plugin in example config
remove quotes in example config to make all statements consistent
logfile: avoid total silence in case of a misconfiguration

Basically the same patch that was applied to syslog.c in 84c38056
correct typo in error message
Merge pull request #619 from Crapworks/master

increased buffer size
write_http: expose more TLS options

* adds support for client certificate authentication
* allows setting CAPath
* allows forcing a specific SSL/TLS version
Store the avl tree within collectd core.

We need this if we want modules to share access to the threshold
avl tree.
reuse main avl tree