Make internals transport and protocol agnostic

[nicklasfrahm]

Currently, the CLI is only able to communicate with Netgear switches via the Netgear Switch Discover Protocol. At its core, the communication with devices can always be seperated into two things:

• Encoding
  The action, either read or write, alongside the desired attributes to be read or written are encoded into a message with a payload. Currently, the library supports TLV (tag-length-value) encoding only.
• Transport
  The encoded message is transmitted over the network using a common network protocol. Currently, the library supports two mechanism, UDP broadcast and UDP unicast. The ports for this are currently hardcoded.

The first step towards improving this is to create the pkg/driver, which defines high-level interfaces. The current idea is to set up multiple RPC services based on the feature, such that there would be the following services for example:

• VLAN: Set up Virtual Local Area Networks
• BandwidthLimit: Limit ingress or egress network bandwidth
• Links: Show status information about network links