Restructure publicip

[bjfelton]

Resubmitting per request. Copy/pasta from the previous PR:

This pull request represents a breaking change to the existing clc_public_ip module.

Now that we've got that out of the way, let me explain what this pull request seeks to accomplish.

1. Restructures module to follow idiomatic, single-resource design (read: it only works on a single server)
2. Adds support for mapping public ip to existing private ip
3. Adds support for specifying port range
4. Addresses issue clc_publicip module Should Support Mixed Protocol Ports #19 by collapsing previous protocol and ports attributes into a single list of dictionaries (ports) that includes protocol (optional, default 'TCP', valid values ['TCP','UDP']), port (required), and port_to (optional) options
5. Removes 'ICMP' protocol since a) it is always enabled and b) providing it without a port to the python-sdk induces an error
6. Adds full test coverage for new code and additional coverage for existing code
7. Updates all related docs and examples

NOTES:

• I have only tested this on a VM's primary network -- more testing should be done when the secondary NIC functionality is finished
• I have confirmed that multiple public ips can be created as long as a private ip is provided on the second (both?) request(s). I did not adjust the docs stating that only a single public ip was possible.