tls support

Hey Guys:

I needed TLS support so I could use log-iss to send logs to papertrail over an encrypted channel.  This actually did the trick!  Was kind of surprised how easy this was in the end.

Lemme know what you think. 
This doesn't actually parse the entire file, so the first block of the pem file could be okay, but others may fail.

I did some digging and this IME the easiest way to make sure that the PEM file is at least properly formatted and that we load stuff from it. There may be (probably is) a better way.

```
import "crypto/x509"

cp := x509.NewCertPool()
if  ok := cp.AppendCertsFromPEM(pemFileData); !ok {
  return nil, fmt.Errorf("Error parsing PEM: %s", pemFile)
}
```