common/config,download: fix URL and relative Windows local file path issues [GH-235] [GH-239]
common/config,download: gofmt fixes
Merge pull request #240 from jasonberanek/windows-paths-fix

common: Fix URL and Relative Windows file path support #235/#239
common: style
Update CHANGELOG
common: replace windows file URL backslash with forward slash

/cc @jasonberanek - Just adding this as well because I see this being
common as well.
website: document {{.Vars}} in execute_command example [GH-241]
builder/amazon/common: refresh instance while connecting to SSH [GH-243]
builder/amazon/all: use new SSHAddress method [GH-243]
builder/amazon/common: be more gentle on AWS API while getting SSHAddr
builder/amazon/common: sleep between API calls for SSHAddr
fix check for vpcid

check for VpcId was incorrectly checking if VPC is empty, instead of not empty.
Merge pull request #245 from extraordinaire/patch-1

builder/amazon/common: fix check for vpcid