v4.0.0-rc1

Changelog

a776414 exclude examples
e58fda3 vendoring deps
45c1f26 try to fix goreleaser
c80cde8 add examples
c167d26 fix #109: remove leaky components; fix #127: make tests stable
8f52d21 issue #124: remove classifier package
5aa317f update readme
cac6d1f Merge branch 'v3' into v4
0d8df3f define go import path for ci
3d37643 Merge branch 'master' into v3
a977c7f remove scrutinizer configuration
fdc0bc8 add description for v4
8607f07 define correct go module
dab0997 update tests
a3ce426 completely switch to go mod
0446f73 switch to v3
032b321 experiments with go mod
8d75960 up required go version to 1.9
42a36ac update deps for retry tool
7ece618 try to fix build on go1.10
2579866 issue #104: add version command
0c2ffff issue #108: define generate script
b8c1d4c issue #104: import github.com/spf13/cobra
d58b933 fix issue #121: make visible cmd/retry for go1.10+
c33b62e add go 1.11
a1441f5 fix research link
197ae3f sync with master