This was introducing a regression with influxdb output, leading to
collision an points missing.
This reverts commit 53f40063.

closes #1724
closes #1796

Previously, the graphite parser would simply overwrite any template that
had an identical filter to a previous template. This included the empty
filter.

Now we will still overwrite, but first we will sort to make sure that
the most "specific" template always matches.

closes #1731

closes #1793

Fixed json serialization to make sure only value type supported by OpenTSDB are sent and made sure we send numbers un-quoted event though OpenTSDB API accepts them as this is not clean json.

closes #1700

Map holding expected results was defined in multiple places, making test
cases a bit hard to read. This way we can change our expectations of
good results in one place and have them affect multiple test cases.

This behaviour was introduced along with socket support, but never got
documented properly.

Added a standard example for collecting interface metrics from switches or routers and tagging them properly.

closes #1666

fixes #1810

closes #1861

Let's align to InfluxDB 1.0 logging policy and log to systemd journal by
default.

closes #1732

Issue #1854

closes #1848
closes #1835

in this commit:

- centralize logging output handler.
- set global Info/Debug/Error log levels based on config file or flags.
- remove per-plugin debug arg handling.
- add a I!, D!, or E! to every log message.
- add configuration option to specify where to send logs.

closes #1786

this will prevent potential very large allocations due to a very large
chunk size send from a client.

fixes #1823

Due to quite real problem of generating vast number of data series through
mesos tasks metrics this feature is disabled until better solution is found.

Tagging values by executor_id can create quite a lot data series
in InfluxDB so we should stick to framework_id and server.

closes #1137

closes #1517

max-repetitions = 10 is the default of net-snmp utils according to
http://net-snmp.sourceforge.net/docs/man/snmpbulkwalk.html

retries = 3 is the default of gosnmp:
https://godoc.org/github.com/soniah/gosnmp#pkg-variables

Could deal with some parts of the performance issues reported
by #1665