Release v0.4.0

[tomdee]

This issue tracks to the v0.4.0 release which will hopefully happen soon.

Please add a thumbs up emoji to this issue if a release is important to you.

The current list of PRs merged since v0.3.0
Testing
#345 travis: roll forward the versions of Go that we test
#314 plugins/noop: return a helpful message for test authors
#328 noop plugin: support multiple CNI_ARGS
#270 Add integration tests of libcni
#269 Refactor skel with dependency injection
#263 plugins/main/ptp: add functional tests
#264 Add Vagrantfile, document how to run test suite in a vagrant VM
#307 testing: test invocation of newer plugins with an older libcni
#308 skel tests: correct name of CNI_CONTAINERID in tests of env vars
#301 A test verifies that libcni is backwards compatible with legacy plugins
#296 Plugins validate cniVersion of NetConf
#298 host-local: fix allocation of last address in a /30
#293 Backfill tests for plugin execution

Docs
#340 Fix README.md host-local IPAM range start/end typo
#312 Add slack badge and link
#311 Update ipvlan.md
#305 Add link to Infoblox IPAM plugin
#304 docs/ptp: fix markdown formatting
#302 3rd party plugins belong in their own repos
#299 List cilium as 3rd party plugin
#295 readme: update link to CloudFoundry usage of CNI
#272 README: distinguish between runtimes and plugins

Spec changes
#247 SPEC: introduce "args" field and new error code
#267 Adds VERSION command
#287 Plugins report a list of supported versions

host local
#115 ipam/host-local: Move allocator and config to backend
#341 host-local: trim whitespace from container IDs and disk file contents
#327 host-local: add DataDir IPAM conf option and use it for testcases
#277 ipam/host-local/allocator tests: cover requested IP
#294 Fix handling of host-local IP address ranges

Other
#344 all: assert internal objects implement interfaces
#335 libcni conf: support .json file extension
#322 Allow flannel CNI plugin stateDir to be configurable
#330 Expand description of goroutine+netns problems
#324 ipvlan: Support L3-Symmetric mode
#290 Fixed the check for network namespace path.
#291 pkg/ip: Ensure that SetupVeth returns correct hostVeth
#241 Add arm64 and ppc64le as new platforms
#273 Reconfigure bridge IP address
#274 Update of netlink version
#280 pkg/ip: Return correct error if container name provided exists, and test cases
#254 pkg/ipam: IP based macaddr
#240 pkg/types: unmarshal string tests
#238 pkg/types: Add UnmarshallableString type