Start using go modules

This is an initial release to start using go modules versions.

What's Changed

• Added function UniqueId which returns a string that uniquely identifies namespace by @amudukutore in #14
• Fixed the docker netns detection err on xenial by @kopwei in #15
• Typo: fix typo in readme by @coolljt0725 in #16
• Add missing stub functions to netns_unspecified.go by @ejj in #18
• Fix typo by @WeiZhang555 in #19
• Add mips, mipsle to the SYS_SETNS map by @vstefanovic in #21
• Fixing README.md by @harche in #20
• fix swallowed err variable by @alrs in #22
• Search kubepods for Docker containers by @theatrus in #24
• Adding new location for containers in recent k8s 1.11+ by @sbezverk in #28
• In contaner path fix by @sbezverk in #29
• add riscv64 architecture by @tonistiigi in #34
• Document that New() changes the current namespace by @povik in #33
• add ns support mips64le arch by @davidstack in #32
• Remove useless setting of new netns from README.md by @matte21 in #31
• Add support for Go modules by @tklauser in #35
• Use golang.org/x/sys/unix instead of syscall by @tklauser in #40
• Set O_CLOEXEC when opening a network namespace by @fanjiyun in #43
• Allows to create and delete named network namespaces by @thomas-maurice in #42
• Add go1.10 build constraint by @brb in #30
• Add support for detecting netns for all possible QoS in Kubernetes by @imilchev in #47
• Extend GetFromDocker() to support also newer distros with cgroup v2 support by @stv0g in #49
• Migrate syscall --> golang.org/x/sys/unix, redux by @jeffwidman in #54
• Update the documentation for netns.NewNamed by @stepchowfun in #56
• Expose named functions when not linux by @WillFantom in #53
• feat: dependabot workflow automation for updating dependency by @Rajpratik71 in #57

New Contributors

• @amudukutore made their first contribution in #14
• @kopwei made their first contribution in #15
• @coolljt0725 made their first contribution in #16
• @ejj made their first contribution in #18
• @WeiZhang555 made their first contribution in #19
• @vstefanovic made their first contribution in #21
• @harche made their first contribution in #20
• @alrs made their first contribution in #22
• @theatrus made their first contribution in #24
• @sbezverk made their first contribution in #28
• @tonistiigi made their first contribution in #34
• @povik made their first contribution in #33
• @davidstack made their first contribution in #32
• @matte21 made their first contribution in #31
• @tklauser made their first contribution in #35
• @fanjiyun made their first contribution in #43
• @thomas-maurice made their first contribution in #42
• @brb made their first contribution in #30
• @imilchev made their first contribution in #47
• @stv0g made their first contribution in #49
• @jeffwidman made their first contribution in #54
• @stepchowfun made their first contribution in #56
• @WillFantom made their first contribution in #53
• @Rajpratik71 made their first contribution in #57

Full Changelog: https://github.com/vishvananda/netns/commits/v0.0.1