create job posting endpoints (intermediate)

```
GET    /jobs		List all jobs
POST   /jobs		Create a new job
GET    /jobs/:id	Get a job
PUT    /jobs/:id	Update a job
DELETE /jobs/:id	Delete a job
```

create the above endpoints for a Jobs page. use the following model for a job:

```
id:integer (rails creates this)
title:string
description:string
phone:string
city:string
state:string
zip:string
email:string
```