Replace all use of rbtree.c with std::map or std::unordered_map

[choll]

No description provided.

[choll]

Removed from HostCache. Todo:

• PortCache
• OUICache
• PPTCPStreamController

[choll]

If using unordered_map http://en.wikipedia.org/wiki/SipHash might be useful to prevent DoS attacks via malicious traffic (i.e. by generating traffic such that keys all collide to a single hash value)