fix(pkg/tiller): saves all previous computed values on reuseValues

Fix #3822

ref(cmd/upgrade): update reuse-values flag descrip

helps clarify behavior. See #3655

Resolves #3655
We were seeing that when running helm upgrade with the reuse-values
flag enabled that you could end up in the position where overrides
a.k.a computed values from previous revisions were not being saved on
the updated revision. This left us in a weird position where some
computed values would disappear mysteriously in the abyss. That
happened because computed values from previous revisions weren't merged
with the new computed values every time the reuse-values flag was used.
This PR merges computed values from the previous revisions so you don't
end up in that kind of conundrum.

ref(cmd/helm): show grpc error msg from prettyError

Fix tiller deployment on RBAC clusters

Removes unnecessary if block

closes #3795

import client auth plugins

Implement before-hook-creation delete policy

Cover hook-succeeded, hook-failed and before-hook-creation hook delete policies.

stream releases when listing

closes #3795

fix output leak from unit tests of helm create command

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

Adds automountServiceAccountToken when a serviceAccount is specified.

Prior to this, tiller falls back to contacting the KUBERNETES_SERVICE on
localhost:8080 rather than respecting the cluster IP in the
KUBERNETES_SERVICE_{HOST,PORT} environment variables.

Fixes #3460, fixes #3467.

Updated kubernetes_distros.md with DC/OS note.

Removed typos (additional plus signs)

ref(*): kubernetes v1.10 support

* 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>

Remove outdated note from doc

Updated kubernetes_distros.md with a note that Helm is running fine on Kubernetes on DC/OS

Update tiller_ssl.md

"that" is duplicated.

Updated to mention the --purge flag on delete

See: https://github.com/kubernetes/helm/issues/2332

add back the default 5 second connection timeout