Fixesspring-projects/spring-integration-samples#198
The `SocketUtils.findAvailableServerSocket()` isn't reliable for port selection and its `socket.close()` may cause a port selection by some other process.
Use OS-selected port for SshdServer in SFTP sample
Revert unexpected refactoring after renaming properties
Upgrade to SSHD-1.4, FTP Server 1.1, fix tests and Boot 2.0 compatibility
JIRA: https://jira.spring.io/browse/INTSAMPLES-137
* Upgrade to Boot 1.1.7
* Fix several Boot apps to get deal with `args`, e.g. `--debug` option can be useful for Boot
* Provide a loca copy for JavaScript files (`sock.js` and `stomp.js`) to avoid extra Internet connection on testing
INTS-137-2: Make JavaScript cross-browser
Some additional polishing to the server config, like `logging-channel-adapter` for server message flow