https://github.com/kubernetes/helm -> https://github.com/helm/helm
https://github.com/kubernetes/charts -> https://github.com/helm/charts



Signed-off-by: Roc Chan <roc@imroc.io>

closes #3795

Now the parsing part is the same as in the curl scenario

Instead of presuming that bash is installed at /bin/bash, use `$PATH`.  Official [bash docker container](https://hub.docker.com/_/bash/) installs bash at `/usr/local/bin` and recommends the use of `env`

HELM_TMP_ROOT directory is now uniquely generated to avoid potential clashes with old installation instances or other processes using the same /tmp subdirectory

Currently the bash script that installs Helm is hard-coded to use
openssl sha command but some distros like Debian 9 only have sha1.
Since the popular current distros have sha1 we can switch to that.

Closes(#2859)

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

$EUID is readonly, so it should be save to test against it.

Thanks for the tip @thomastaylor312 !

Avoid using $* multiple times

If the execution user is already the root user, this avoids requireing
sudo to be installed within the environment. Which might helo in CI
environments.

This change prevents downloading the same version as already installed.

shasum is not on many platforms (like centos), use openssl instead.

Downloading of charts and helm itself happened over http. This
change moves to use https as that is available with valid certs.

A bucket name in the path can be migrated to a custom k8s domain
name. This is in preperation for that.

This adds 'scripts/get`, which is a bash script for fetching and
installing the Helm client. It has the following features:

- It uses the GitHub API to discover the latest release
- It downloads the SHA256 checksum and verifies the binary using it
- It does basic tests on the installation