Missed these on my PR last night

Closes #2527

When a repository is generated without --url, the packages in that
repository do not have FQDNs. In this case, the URL prefix (FQDN plus
base path) should be derived from the repository's base URL. This seems
to be a regression that crept in around Helm 2.2.0. This is now fixed.

Closes #2315
Closes #2510

Remove incorrect statements in charts.md about nested globals not being allowed.

Add FAQ for `unsupported protocol scheme ""` error

2.4.0 stopped installing development versions by default. This allows
the user to re-enable that support by setting --devel.

Closes #2407

* Adds update option to plugin command

Fixes issues/2385 - helm install silently updates the plugin, if it pre-existed

* Added tests for new methods for plugin update

* Updated docs

* Updated review comments :)

* Return error exit code when there is error

With hook weights, execution ordering can be built.

helps with half of #2224

Updated the 'helm completion' command to take in the shell
as a parameter. Currently acceptable options are 'bash' and
'zsh'. Also fixed the completions to work with zsh in a manner
similar to what kubectl does.

Also updated the docs to reflect this change.

Closes #2201

Closes: #2343

Closes #2234

Protoc was updated a little while ago and we are likely to get more
people using it. This should avoid weird merge conflicts and bump us
to the latest version

It is now possible to create plugins with chart download capabilities for custom, non-http protocols.
Furthermore it is possible to reuse helm packages to implement alternative clients with these custom downloader functions.

A lot of community members are looking at `helm serve` as a production webserver to host their
charts. There are much better solutions out there like s3, wabs or gcs for cloud storage and
nginx, haproxy or apache for DIY dedicated web servers. Steering users in the right direction
will help users make the right decision when it comes to serving their charts in production.

Added a note that helm needs to be in a
specific directory path in order for it
to be compiled.