Make failures to connect via Socks5() more informative and less unnecessarily scary.

• The "ERROR" was printed far too often during normal operation for what was not an error.
• Makes the Socks5() connect failure similar to the IP connect failure in debug.log.

Before:
2016-05-09 00:15:00 ERROR: Proxy error: host unreachable

After:
2016-05-09 00:15:00 Socks5() connect to t6xj6wilh4ytvcs7.onion:18333 failed: host unreachable"