Correct copyright notices and simplify license.

Correct copyright notices and simplify license.

The copyright notices on Open vSwitch files have until now often called
Stanford University the copyright holder.  This is incorrect, and it has
never been correct.  Nicira Networks is the correct copyright holder, and
always has been.

At one time, Nicira considered contributing the copyright on Open vSwitch
(then known as the OpenFlow reference implementation) to Stanford
University as part of the formation of the OpenFlow Consortium at Stanford.
However, no copyright assignment paperwork was ever prepared or signed.
In the United States, transfer of copyright must be in writing, according
to Title 17 chapter 2 section 204(a):

    A transfer of copyright ownership, other than by operation of law, is
    not valid unless an instrument of conveyance, or a note or memorandum
    of the transfer, is in writing and signed by the owner of the rights
    conveyed or such owner's duly authorized agent.

Thus, Nicira Networks remains the copyright holder of Open vSwitch source
code prepared by its employees.  The commit logs show no significant
contributions by non-Nicira employees (including Stanford employees), so
we conclude that properly the copyright notices should refer to Nicira
Networks, not Stanford.