builder/digitalocean: Updated DigitalOcean default image id

provisioner/chef-solo: Chef environment doesn't work for chef-solo

provisioner/puppet: fix crash when HieraConfigPath or ManifestDir is specified in the config file.

Prevents the following error,
Build 'amazon-instance' errored: template: tpl11:1:103: executing "tpl11" at <.HieraConfigPath>: HieraConfigPath has arguments but cannot be invoked as function

It looks like DigitalOcean replaced the "Ubuntu 12.04" image with "Ubuntu 12.04.3".  We've updated the ImageID to point to the new image.

The required go version to build packer seems to be 1.2

Check if the installed version is greater than the required version. Error out if that's not the case

Change the documentation accordingly. 'ne' template function was added as part of go 1.2.
http://golang.org/doc/go1.2#text_template

Google Compute Builder