Site still references ember-fastboot-server

[danmcclain]

Tis deprecated, we need to update documentation

[davidpett]

referenced in the following places:

• [ ] https://github.com/ember-fastboot/fastboot-website/blob/master/markdown/docs/user-guide.md#the-fastboot-server
• [ ] https://github.com/ember-fastboot/fastboot-website/blob/master/markdown/docs/deploying.md#from-the-command-line
• [ ] https://github.com/ember-fastboot/fastboot-website/blob/master/markdown/docs/deploying.md#as-a-middleware