fix(docs): fix code comment for ReuseValues()

Update related.md

Add helm-gcs plugin

feat(tiller): exposes port 44135 in tiller deployment

feat(helm): Automatically execute helm dep up when charts are in requirements.yaml but not in charts

Tiller exposes probes and metrics in 44135. Because tiller doesn't expose that port and does not contain any Prometheus annotations, making Prometheus scrape tiller is a bit more complex.

Closes #2985

feat(helm): Add a flag --dep-up that helm install will automatically execute helm dep up when charts are in requirements.yaml but not in charts

If checkdependencies returns an error, we can start download the
charts which are not in charts.

Closes #2879

docs(chart): add notes regarding `.helmignore` and `.Files`

docs(templates): fix misleading/broken examples

Allow to specify socket for rudder grpc server

feat(search): Expose AppVersion in search results

Fix typo for --service-account

feat(chart): Adding maintainer url

fix(circleci): Fixing the glide/vendor cache so it is used by glide

Dependencies installation doc

Add docs clarification to resolve #3046

Update using_helm.md

This commit does a few things:
* It moves the information being cached to be the glide cache.
  This will make the glide install process faster.
* The cache is restored from prior to installing the dependencies.

add version flag to tiller binary

* TODO comment on tiller.go

Update

docs: Using Helm in Openshift Kubernetes distribution

Some would like to expose and see the application version in the
search results. This change displays it.

Closes #3010

Each maintainer can have an optional URL. There are seceral use
cases for providing a URL instead of an email address:
- The case where a maintainer wants to hide their email address
  behind a webform for personal security
- When the maintainer is an organization and feedback should
  go to an issue queue

This change:
- Adds the proto field for url
- Updates the generated files for the chart proto
- Includes linting for the url
- Updates the docs to include the url

Closes #3056

docs(tiller): Adds documentation for secret backend

fix circle not building tags

CircleCI recently skipped building tags by default, so we need to
explicitly enable it.

See https://circleci.com/docs/2.0/configuration-reference/#tags

Adding documentation on $ variable scope

as requested