Remove database host config for Linux support
Remove database host config for Linux support

Problem:

Ubuntu (and possibly other Linux distributions)
don't recognize `localhost` as a valid host parameter
in `config/database.yml`.

Running `bin/setup` gives them the error:

```
Couldn't create database for {"adapter"=>"postgresql",
"database"=>"administrate-prototype_development",
"encoding"=>"utf8",
"host"=>"localhost",
"min_messages"=>"warning",
"pool"=>2,
"timeout"=>5000}
```

Solution:

Remove the `host` key from `config/database.yml`.

Without the `host` key, OS X defaults to `localhost`
and Ubuntu defaults to its Linux-y equivalent.

flama/administrate,gustavo-alb/administrate,acrogenesis-lab/administrate,tmecklem/administrate,vgsantoniazzi/administrate,micapam/administrate,BenMorganIO/administrate,gustavo-alb/administrate,flama/administrate,nando/administrate,nburkley/administrate,nburkley/administrate,acrogenesis-lab/administrate,micapam/administrate,kpheasey/administrate,kpheasey/administrate,tmecklem/administrate,flama/administrate,thoughtbot/administrate,nburkley/administrate,dminchev/administrate,BenMorganIO/administrate,BenMorganIO/administrate,kpheasey/administrate,astarix/administrate,joshua5201/administrate,flama/administrate,kpheasey/administrate,vgsantoniazzi/administrate,gustavo-alb/administrate,vgsantoniazzi/administrate,vgsantoniazzi/administrate,acrogenesis-lab/administrate,dminchev/administrate,joshua5201/administrate,TheHumanEffort/administrate,tmecklem/administrate,dminchev/administrate,astarix/administrate,joshua5201/administrate,astarix/administrate,tmecklem/administrate,micapam/administrate,thoughtbot/administrate,micapam/administrate,acrogenesis-lab/administrate,gustavo-alb/administrate,joshua5201/administrate,TheHumanEffort/administrate,dminchev/administrate,TheHumanEffort/administrate,thoughtbot/administrate,nando/administrate,nando/administrate,nando/administrate,TheHumanEffort/administrate,thoughtbot/administrate,astarix/administrate,BenMorganIO/administrate,nburkley/administrate