Add Triton Volumes support

[nimajalali]

This PR relies on terraform-provider-triton supporting Triton Volumes. Tracked here.

While support for Triton Volumes is rolling out you can still run/test this branch by manually building/installing terraform-provider-triton locally. Then running terraform in the same path as the terraform-provider-triton binary.

Checkout and install terraform-provider-triton

go get github.com/terraform-providers/terraform-provider-triton
cd $GOPATH/src/github.com/terraform-providers/terraform-provider-triton
git remote add nimajalali https://github.com/nimajalali/terraform-provider-triton
git fetch nimajalali
git checkout nimajalali/add-support-for-volumes
go install

Download Terraform into $GOPATH/bin

cd $GOPATH/bin
wget "https://releases.hashicorp.com/terraform/0.11.5/terraform_0.11.5_darwin_amd64.zip"
unzip terraform_0.11.5_darwin_amd64.zip

Run triton-kubernetes with terraform-binary flag

cd $GOPATH/src/github.com/joyent/triton-kubernetes
git remote add nimajalali https://github.com/nimajalali/triton-kubernetes
git fetch nimajalali
git checkout nimajalali/triton-volumes
go build
SOURCE_URL=$GOPATH/src/github.com/joyent/triton-kubernetes ./triton-kubernetes create manager --terraform-binary $GOPATH/bin/terraform

@fayazg