cni v0.6.0

Merge pull request containernetworking#427 from squeed/convention-cha…

…ining

Conventions: add convention around chaining interfaces

Merge pull request containernetworking#419 from asridharan/cnitool

Added documentation for `cnitool`

spec/plugins: fix 'ip'->'ips' in the spec, bump to 0.3.1

Merge pull request containernetworking#412 from tomdee/safe-del

plugins/*: Don't error if the device doesn't exist

Merge pull request containernetworking#366 from ehazlett/ipam-host-lo…

…cal-initial-reserved-ip

Do not error if last reserved not found after initial creation

Merge pull request containernetworking#387 from tangle329/master

Check n.IPAM before use it in LoadIPAMConfig function

spec,libcni: add support for injecting runtimeConfig into plugin stdi…

…n data

Add a new CapabilityArgs member to the RuntimeConf struct which runtimes can
use to pass arbitrary capability-based keys to the plugin.  Elements of this
member will be filtered against the plugin's advertised capabilities (from
its config JSON) and then added to a new "runtimeConfig" top-level map added
to the config JSON sent to the plugin on stdin.

Also "runtime_config"->"runtimeConfig" in CONVENTIONS.md to make
capitalization consistent with other CNI config keys like "cniVersion".