Adds the `required` function in enginge.go to support required
properties in values.yml. When a chart developer wishes to specify
intent in requiring a value, they can use this function to declare
an error message that gets returned when chart rendering fails
when a required value is not present in values.yml.

Closes #1580

docs(chart_best_practices): create best practices guide

Clarify inheritance behavior for global variables

fix checksum example

This adds a basic Chart Best Practices guide.

Closes #1993

$.Template.basePath already contains "templates/"

Add .Template.BasePath to template system

install: Return more user-friendly response on eexists

Fix helm dep list reporting wrong status

docs(related): Add link to helm-diff plugin

Link to the Helm Chart repository from the Helm project

Add toToml template function

Version matching is used for checking status of subcharts.
closes: #2056

The current README makes no mention of the Chart repository or where to find it. You have to Google to find it or stumble upon it. It was frustrating to come to the Helm project and not easily be able to find where the chart repository was - even though I knew it existed. This patch will make that easier for others.

fix(tiller): Fixes `--wait` panic on upgrade

Most newcomers hit helm's 'feature' there deleted instalations are not really deleted.
Use-case
# helm install  --name gitlab-ce-1 ./stable/gitlab-ce
# helm delete gitlab-ce-1
# helm list
# helm install  --name gitlab-ce-1 ./stable/gitlab-ce
Error: a release named "gitlab-ce-1" already exists

There is a lot duplicated bugs in bugzilla which simply explains that packages
should be deleted with --pure flag. But such bugs appeared again and again
because this behavior is not obvious.

Let's help user to figure out what happens ASAP.

local path repo verbose - issue #2020

When manifests do not change, they didn't get populated with the
latest label info from the API server and then panic'd. This resolves
that bug

Closes #2043

expose LoadFiles as a usable function

Fix typo singing -> signing

feat(helm): add --skip-refresh flag to 'helm dep up'

In third-party libraries, charts can be embedded in memory rather than in files, directories or
tarballs. Exposing LoadFiles allows a third-party library the ability to load static templates
in and spit out a *chart.Chart.

docs(related): add KubeCon 2016 videos

close #2023

docs(related): add cog-helm to 'Additional Tools'

fix(helm): add message if release deleted successfully

docs(wrapping_up): fix broken link to Tips and Tricks

kubernetes has explicit delete message that user can know resources being deleted for sure,
suggest also add this behavior to helm, as it is too 'quiet' for deletion operation right now.