Sugar 0.4.0: Server SSH key verification

Sugar now consults the server console to detect the SSH hostkey fingerprints, stores them in an EC2 tag for future reference, and adds the keys to the local system to bypass the yes/no prompt while improving security. It also auto-detects the username to use when connecting to the server.

This feature is still somewhat experimental.

Version 0.3.3; update README

0.3.2: Add public/private dns/ip instance filters

Bump version to 0.3.1

Bump version to 0.3.0

Main difference is a new `-f` flag for bringing a remote port to the
local machine.

Environment variable clash is bad. 0.2.3

Support .pem for private keys, bump to 0.2.0

Bump version to 0.1.4