When a user enters a non-URL (such as stable)
in requirements.yaml and tries to `helm dep up`,
they get a potentially confusing error message.
This tries to make the error message clearer.
Closes#2672
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.
The following commands:
helm dep update
helm dep build
are now able to take a requirements.yaml with dependency charts' repo defined as:
file://../local/path or file:///root/path
closes: #1884