Fix Rows all by default

So, it turns out the rows parameter doesn't work as a header, you have to do it as a URI parameter.

So I've changed the rows to use 'all' by default.

Also, fixed a bug with the `unless name` bit. Currently this will not work:

```ruby
puts connection.find(:type => 'host', :name => 'foo')
```

```
/Users/peters/projects/opsview_rest/lib/opsview_rest.rb:98:in `find': undefined local variable or method `name' for #<OpsviewRest:0x007ff2926176c8> (NameError)
	from pkg/test.rb:5:in `<main>'
```

So fixed that as well :+1: