AWS SQS signature mismatch and Excon warning fixes

Attempting to perform SQS operations in 1.19.0 fails with the following error because commit 8c5ea5d removes the `host` and `port` needed to generate the signature correctly:

```
#<Excon::Response:0x007fdfcdecdb78 @data={:body=>"<?xml version=\"1.0\"?><ErrorResponse xmlns=\"http://queue.amazonaws.com/doc/2009-02-01/\"><Error><Type>Sender</Type><Code>SignatureDoesNotMatch</Code><Message>The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.</Message><Detail/></Error><RequestId>3c3fbde1-cc14-5255-9d5d-f6a76af4f112</RequestId></ErrorResponse>", :headers=>{"Server"=>"Server", "Date"=>"Wed, 08 Jan 2014 01:06:40 GMT", "Content-Type"=>"text/xml", "Content-Length"=>"436", "Connection"=>"close", "x-amzn-RequestId"=>"3c3fbde1-cc14-5255-9d5d-f6a76af4f112"}, :status=>403, :remote_ip=>"72.21.202.145"}, @body="<?xml version=\"1.0\"?><ErrorResponse xmlns=\"http://queue.amazonaws.com/doc/2009-02-01/\"><Error><Type>Sender</Type><Code>SignatureDoesNotMatch</Code><Message>The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.</Message><Detail/></Error><RequestId>3c3fbde1-cc14-5255-9d5d-f6a76af4f112</RequestId></ErrorResponse>", @headers={"Server"=>"Server", "Date"=>"Wed, 08 Jan 2014 01:06:40 GMT", "Content-Type"=>"text/xml", "Content-Length"=>"436", "Connection"=>"close", "x-amzn-RequestId"=>"3c3fbde1-cc14-5255-9d5d-f6a76af4f112"}, @status=403, @remote_ip="72.21.202.145">
```

I've rolled back that commit and removed `host` from the request args being passed to Excon, which was generating a warning.