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.
Fix a few typos
CPU Percentage: after realloc the pointer becomes invalid; need to work on new pointer.

fixes https://gist.github.com/toni-moreno/a2f80021535f87202de7
Fix the conversion of time option in PUTNOTIF
	from timestamp to cdtime_t
Plugin java: fix notification time conversion to cdtime_t.
Plugin threshold: time is not set in missing notifications.
cmd PUTNOTIF time option: handle double values.
FLUSH cmd: convert timeout (double) to cdtime_t
  as the previous call to plugin_flush
amqp: new Queue{Durable,AutoDelete} options are subscribe-only options
document 2 new options added to amqp plugin
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
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