Add crypto utilities for encryption feature.
Fixed bugs related to wrong assert's conditions.
Move gossip's data into dmsg's payload so that we can use dmsg's data to store encryption aes key.
Add -g option to disable gossip for testing
Enhance and fix dnode msg's response wrapped with header.
Supporting AES encryption with AES key attached long the msg.
Will encrypt the AES key with RSA key later.
Support encrypting AES key with RSA key
Use directive to not include some debugging lines into the binary code
Make pem file location configurable
Optimizing AES key exchanging by sending it once
Merge pull request #57 from timiblossom/crypto

Crypto
Fix indentations.
Default gossip to disable and turn it on by '-g' parameter
Merge pull request #58 from timiblossom/crypto

Fix indentations.