Release 2.0.2

Release v2.0.1.

Arduino Zero can't use W5100-based shields with SCK > 8 MHz

Added some other entries in the AUTHORS file

UdpNtpClient example: removed wrong return type

Expose optional DHCP timout parameters to Ethernet:begin()

A no brainer update.
Expose optional timeout parameter values of dhcp for user to adjust on
their code.
Currently if dhcp server is not available, code will block inside
DhcpClass::request_DHCP_lease() for 60s. Having this parameters exposed
user can specify their timeout requirements without changing the lib
code.
Change is backward compatible as parameters are optional and defaults to
existing values.

Ethernet: Increased version number

Ethernet: releasing version 1.0.4

Due to website configuration changes, every url starting with http://…

…arduino.cc has been changed to http://www.arduino.cc. Fixes #3191

Libraries: added help files to mitigate missing contextual reference …

…issue