Automatic merge from submit-queue (batch tested with PRs 37708, 34410)
Add restclientconfig helper fn for parsing timeout
Related downstream PR: https://github.com/openshift/origin/pull/12062 (example of use-case for this patch)
**Release note**:
```release-note
release-note-none
```
This patch adds a package `pkg/client/unversioned/clientcmd/util` and
defines a `ParseTimeout` helper function for parsing time from a
user-defined string. This allows code re-use in other packages that
require the creation of a new restclient (and therefore must set the
`--global-timeout` flag value manually).
@fabianofranz @kubernetes/cli-review
4d467de5c5