Fix(helm): Fix the bug of dependency update deleting subcharts

Merge branch 'fix-update-delete-subcharts' of https://github.com/rocky-nupt/helm into fix-update-delete-subcharts

feat(*) add key helm.sh/hook-delete-policy to hook annotation

In Helm 2.6.0, the new delete feature that deletes old versions of
charts is deleting subcharts that aren't in requirements.yaml.
In this patch, I judge the dependency whether it is included in the
requirements.yaml before deleting it.

Closes #2830

When "helm.sh/hook-delete-policy: hook-succeeded" is provided in a hook's annotation, Tiller will automatically delete the hook after the hook is succeeded. When "helm.sh/hook-delete-policy: hook-failed" is provided in a hook's annotation, Tiller will automatically delete the hook after the hook is failed.

Closes #1769

fix typo in helm_fetch.md

Fix curl error Failed writing body

feat(tiller): limit number of versions stored per release

* feat(2450): add options to chart metadata

fix(CONTRIBUTING): added note about who merges a PR

feat(helm):Support reading the values file from STDIN

Delete old deps after chart deps are updated

We can use the command like
<pre>sed "s|foo|bar|g" values-template.yaml | helm install -f - stable/foo</pre>

This may be helpful in scripting.

Closes #2709

feat(tiller): sort manifests alphabetically if they are same kind

Remove length check from subsort test. Add check for unknowns.

Updates Tiller manifest sorting so that manifests of the same kind are
then sorted alphabetically.

Closes #1696

Fix the default NOTES.txt and values.yaml

Fix Typo in Contributing Guidelines

Do not close the pipe early, output only the first version found.  wget command changed for consistency.
Fixes #2802

Add nebril to OWNERS

This adds a new configuration option to Tiller to limit the number of
records stored per release.

Tiller stores historical release information (helm history, helm
rollback). This makes it possible to set a maximum number of versions
per release.

To enable this feature, use `helm init --history-max NNN`. Note that
because of the restrictions on Deployment objects, you will have to
re-install Tiller to add a limit.

Along the way, I found an unreported bug in the Memory storage driver.
This fixes that bug and adds substantially more tests to catch
regressions.

Closes #2332

This change changes the order of operations in
pkg/downloader.Manager.downloadAll

Old charts are moved to tmp directory which is restored in case any
dependency update fails. Otherwise tmp dir is deleted.

updated pullpolicy example

Unsupported value: "alwaysPull": supported values: Always, IfNotPresent, Never

chore(docs): add guide for service accounts

feat(helm):use a variable for labels to get tiller pod

Redefine the err variable in NewChartRepository, otherwise errors migh slip through

fix(pkg/strvals): preserve leading zeros in vals

Add link to wheel.

Updating default values.yaml comments

Add godoc reference badge

Add requirements.yaml to Charts file structure