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

fixes https://gist.github.com/toni-moreno/a2f80021535f87202de7
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
Merge branch 'master' into feature-riemann-threshold
make threshold checking optional
document new options
Add a write_kafka output with similar properties to the amqp one.
remove unneeded include
make kafka logs go through collectd's logging
Merge pull request #666 from KiNgMaR/write_http-ssloptions

write_http: expose more TLS options
Merge pull request #639 from dothebart/fix_cpu_crash

CPU Percentage: after realloc the pointer becomes invalid;