ref(chartutil): move chart loading out of chartutil into new package
    add chart loader interface to allow lazy loading
feat(chart): create chart accessors
ref(*): cleanup requirements
ref(tiller): remove optional template engines
ref(tiller): simplify sorting releases and hooks
ref(*): code simplification
ref(hapi): move chart package out of hapi
ref(chart): add requirements and lock to Chart struct

* fix(helm): fix golint warning due to ApiVersionV1 constant name

Signed-off-by: Arash Deshmeh <adeshmeh@ca.ibm.com>

* fix(helm): fix golint warning due to ResolveChartVersionAndGetRepo comment

Signed-off-by: Arash Deshmeh <adeshmeh@ca.ibm.com>

* fix(helm): fix golint warnings on HttpGetter type and SetCredentials method missing a comment

Signed-off-by: Arash Deshmeh <adeshmeh@ca.ibm.com>

* fix(helm):fix golint warning due to comment on FindChartInAuthRepoURL function

Signed-off-by: Arash Deshmeh <adeshmeh@ca.ibm.com>

* fix(helm): fix golint warning due to RepoFile type name

Signed-off-by: Arash Deshmeh <adeshmeh@ca.ibm.com>

* fix(helm): fix golint warning due to ParseString comment

Signed-off-by: Arash Deshmeh <adeshmeh@ca.ibm.com>

Authentication support for remote charts repositories.

New users to helm don't always run `helm init` (e.g. if their cluster
already has helm installed).  The user's initial interaction with any of
helm's repository commands (e.g. `helm repo list`) will then be an error
message due to a missing repositories.yaml in their local config.

Give the user a little hint about how to fix the error without them having
to hunt through the man/help pages.

* Closes #2937
Added required dependency to run make test in developer's guide

* Fixed base URL appending when chart address is not absolute

* Removed requirement from developers.md

* Fixed unnecessary line breaks

* Added tests for query string repo

* Returning URL along with error

This reverts commit 965cb7fd.

This prevents clients from seeing half-written files because
on POSIX systems renaming a file is an atomic operation.

Drive-by: Add test for repo file permission.

- [ ] Added tests for --repo flag on `helm fetch` command
- [ ] Also added tests for (pkg/repo).FindChartInRepoURL

This flattens the getter package tree, adds tests, and changes a little
bit of the terminology to follow Go idioms. This also makes much of the
getter API private to begin with. This will give us more flexibility in
the future.

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.

This exposes the skip-refresh flag to helm init to make it possible to
initialize Helm without fetching the index.yaml of the stable repo.
This mirrors the behavior of 'helm dep up's skip-refresh flag.

Closes #2127

This change sorts the helm index file after downloading from a repo.

Closes #2186

Added tests for:
- [ ] pkg/version/versions.go
- [ ] pkg/repo/repo.go

When downloader package moved to under /pkg, helmpath functions got called still from it, while it is under /cmd. This commit fixes the issue by moving helmpath after the downloader to have only cmd->pkg and pkg->pkg calls.

A regression was committed during 2.2.0 that broke the repositories.yaml
file format, switching the cache path from relative to absolute. This
fixes the error.

Closes #1974

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.

Closes #1522