Network library

[vzahradnik]

Is your feature request related to a problem? Please describe.
Write a networking library which will abstract all the different boards or shields and which will allow simple interaction with the network.
Features:

• DHCP and static IP mode
• Automatic connection handling and reporting
• The system interacts with the networking module via simple interface, e.g. isOnline(): Boolean
• Support for DNS resolution. Users can either use IPs or domain names and the system will resolve an IP
• Support for mDNS so that the device can be seen in the internal network, the name could be configurable
• NTP support... this could be moved into another library handling time, date and timezones. To be discussed further.