Added support for own hostnames and pathStyle Requests

Added support for own hostnames and pathStyle Requests in order to use "third-party" s3 services. (e.g. ceph or swift).  

```
      s3 = UberS3.new({
                          :access_key         => 'secretkey',
                          :secret_access_key  => 'secret',
                          :bucket             => 'testbucket3',
                          :adapter            => :em_http_fibered,
                          :pathStyle			=> true,
                          :host					=> '127.0.0.1:80'
      })
```
If "host" oder "pathStyle" are not set the client connects to s3.amazonaws.com as usual and used dns-style requests on buckets.