Add support for vagrant-docker (#389)

* clean trailing ws in Vagrantfile and util/avr_setup.sh

* replace triple quotes with heredoc.

Ruby doesn't have triple quotes; that's a Python thing. This was just being
parsed as multiple strings concatenated.

* add docker support to Vagrantfile

* make wants to find dfu-programmer in vagrant guest

Vagrantfile

@@ -62,6 +62,16 @@ Vagrant.configure(2) do |config|
     vmf.memory = "512"
   end
 
+  # Docker provider pulls from hub.docker.com respecting docker.image if
+  # config.vm.box is nil. Note that this bind-mounts from the current dir to
+  # /vagrant in the guest, so unless your UID is 1000 to match vagrant in the
+  # image, you'll need to: chmod -R a+rw .
+  config.vm.provider "docker" do |docker, override|
+    override.vm.box = nil
+    docker.image = "jesselang/debian-vagrant:jessie"
+    docker.has_ssh = true
+  end
+
   # This script ensures the required packages for AVR programming are installed
   # It also ensures the system always gets the latest updates when powered on
   # If this causes issues you can run a 'vagrant destroy' and then
@@ -70,7 +80,7 @@ Vagrant.configure(2) do |config|
 
   config.vm.provision "shell", run: "always", path: "./util/avr_setup.sh", args: "-update"
 
-  config.vm.post_up_message = """
+  config.vm.post_up_message = <<-EOT
   Log into the VM using 'vagrant ssh' on OSX or from Git Bash (Win)
   or 'vagrant ssh-config' and Putty or Bitvise SSH or another SSH tool
 
@@ -84,5 +94,5 @@ Vagrant.configure(2) do |config|
   cd /vagrant; cd keyboard; cd ergodox_ez; make clean; make
 
 
-  """
+  EOT
 end

util/avr_setup.sh

@@ -38,6 +38,7 @@ elif [[ -n "$(type -P apt-get)" ]]; then
     gcc-avr \
     binutils-avr \
     avr-libc \
+    dfu-programmer \
     dfu-util
 
 elif [[ -n "$(type -P yum)" ]]; then
@@ -55,6 +56,7 @@ elif [[ -n "$(type -P yum)" ]]; then
     avr-binutils \
     avr-gcc \
     avr-libc \
+    dfu-programmer \
     dfu-util
 
 elif [[ -n "$(type -P zypper)" ]]; then