provider/aws: fix panic when user_data receives nil from StateFunc
Merge pull request #222 from ryanuber/bugfix-aws-statefunc

provider/aws: fix panic when user_data receives nil from StateFunc
helper/schema: one of Optional, Required, Computed must be set
helper/schema: update docs
command/apply: keep track of default variables separately [GH-153]
Fix go vet complaints
Use scanner instead of buffer read line

Supported in Go 1.1 http://golang.org/pkg/bufio/#Scanner
Merge pull request #225 from desimone/patch-1

provisioners/remote-exec: Use scanner instead of buffer read line
providers/mailgun: initial commit
website: add docs for mailgun provider
providers/mailgun: smtp_password is required
providers/mailgun: clarify domain docs
providers/mailgun: smtp_password is required, no need for pub api key