argument and verb formatting fixes reported by go vet

builtin/providers/aws/tags_test.go:56: unrecognized printf verb 'i'
builtin/providers/aws/tags_test.go:59: unrecognized printf verb 'i'

config/config_test.go:101: possible formatting directive in Fatal call
config/config_test.go:157: possible formatting directive in Fatal call

config/module/get_file_test.go:91: missing argument for Fatalf(%s): format reads arg 1, have only 0 args

helper/schema/schema.go:341: arg v.Type for printf verb %s of wrong type: schema.ValueType
helper/schema/schema.go:656: missing argument for Errorf(%s): format reads arg 2, have only 1 args
helper/schema/schema.go:912: arg schema.Type for printf verb %s of wrong type: schema.ValueType

terraform/context.go:178: arg v.Type() for printf verb %s of wrong type: github.com/hashicorp/terraform/config.VariableType
terraform/context.go:486: arg c.Operation for printf verb %s of wrong type: terraform.walkOperation

terraform/diff_test.go:100: arg actual for printf verb %s of wrong type: terraform.DiffChangeType
terraform/diff_test.go:235: arg actual for printf verb %s of wrong type: terraform.DiffChangeType
Merge pull request #535 from ceh/vet-fixes

argument and verb formatting fixes reported by go vet