Mail renderer doesn't know routes

[lukasschlueter]

Steps to Reproduce the Problem

Minimal setup:

1. Create a new project
2. Run buffalo g mailer Test
3. Add SMTP credentials to .env
4. Add handler that calls the new mailer, e.g.

app.GET("/send", func(context buffalo.Context) error {
	return mailers.SendTest()
})

5. Specify mail receiver in mailers/test.go
6. Edit templates/mail/test.html to include something like Website root : "<%= rootPath() %>"
7. Open localhost:3000/send

Expected Behavior

Buffalo sends a mail to the specified email address containing Website root: "/".

Actual Behavior

Buffalo fails to render the template with the following error: test.html: line 3: rootPath: unknown identifier

Info

### Buffalo Version
v0.12.6

### App Information
Pwd=C:\Users\Lukas\go\src\gitlab.com\lukas-schlueter\test
Root=C:\Users\Lukas\go\src\gitlab.com\lukas-schlueter\test
GoPath=C:\Users\Lukas\go
Name=license_server
Bin=bin\license_server.exe
PackagePkg=gitlab.com/lukas-schlueter/test
ActionsPkg=gitlab.com/lukas-schlueter/test/actions
ModelsPkg=gitlab.com/lukas-schlueter/test/models
GriftsPkg=gitlab.com/lukas-schlueter/test/grifts
VCS=git
WithPop=true
WithSQLite=true
WithDep=false
WithWebpack=true
WithYarn=true
WithDocker=true
WithGrifts=true

### Go Version
go version go1.11 windows/amd64

### Go Env
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\Lukas\AppData\Local\go-build
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=C:\Users\Lukas\go
set GOPROXY=
set GORACE=
set GOROOT=D:\Programs\Go
set GOTMPDIR=
set GOTOOLDIR=D:\Programs\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=C:\Users\Lukas\go\src\gitlab.com\lukas-schlueter\test\go.mod
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\Lukas\AppData\Local\Temp\go-bui
ld962895198=/tmp/go-build -gno-record-gcc-switches

### Node Version
v8.11.1

### NPM Version
5.6.0

### Yarn Version
1.9.4

### PostgreSQL Version
PostgreSQL Not Found

### MySQL Version
MySQL Not Found

### SQLite Version
SQLite Not Found

### Dep Version
could not find a Gopkg.toml file

### Dep Status
could not find a Gopkg.toml file

[kteb]

As @paganotoni was busy I start working on it. I managed to have it on a local app, need to refactor it a bit and integrate it to the generator. I hope to have it for this week-end.

[markbates]

fixed with #1338