Prior to merging the projects, the version of `helm deploy` used a
different REST API (one without YAML in JSON). Post-merge, we need to
revert back to the older common.Template version.

As part of this, I switched an io.ReadCloser back to an io.Reader
because there is nowhere where the Closer part is used. The http lib
does not close a reader passed to it.

This fixes a number of formatting and style issues.

Closes #370

Closes #311.

This re-jiggers the deployment to use common.Configuration. Right
now it will not work, since the remote server expects a common.Template
instead of a common.Configuration. Still trying to figure out which
side to change.

Also made an HTTPError error type to make it easier to type
switch on errors.

Cleaned up some of the code we inherited from DM.

Also, remove a whole bunch of unused functions.