* fix: Update gRPC to get better TLS connection handling

To avoid backward compatibility breakers, we have been pinned to a very
old version of gRPC. But it appears that there have been some very
significant network fixes since then. Looking closely at #3480, it
appears that some of this fixes may be directly related to solving that
bug.

Note that this regenerates a few of the Go proto files, so the binary
wire format may be broken. That means this MUST be held to a minor
version, not a patch release.

To test:

- Build both client and server
- Install Tiller into your cluster
- Perform a number of Helm-Tiller interactions (`helm version`, `helm
list`)

Closes #3480
Signed-off-by: Matt Butcher <matt.butcher@microsoft.com>

* Switched to latest protobuf
Signed-off-by: Matt Butcher <matt.butcher@microsoft.com>