Previously, we published builds to rel.pulumi.com and only put actual
released builds (eg. rc's and final builds) on get.pulumi.com. We
should just publish all of the SDK builds to get.pulumi.com.
This also makes a slight tweak to the filename of the package we
upload (we took the switch over to get.pulumi.com to make this change
and now that we are uploading automatically, we need to encode this
change instead of doing it by hand).
This change eliminates our dependencies on the SDK repo. Now that
SDKs are comprised solely of pulumi/pulumi artifacts, a separate repo
isn't required. This allows us to simplify some of the distribution.
The install.sh script is modified slightly, to permit overriding the
default install location using $PULUMI_INSTALL_PATH.
