Better error messages

[arkena00]

Check the existence of pem files when reading the configuration.

It will provide a better error than the one in trantor (FATAL No such file or directory - TcpConnectionImpl.cc:140 )

[rodyherrera]

I solve this error in the following way ..., in the .json that you load in the main of your project, note that it brings an "ssl", you must eliminate the content of "cert" and "key". Before: "ssl": { "cert": "../../trantor/trantor/tests/server.pem", "key": "../../trantor/trantor/tests/server.pem", "conf": [ ] }, After: "ssl": { "cert": "", "key": "", "conf": [ ] },