recoco: Fixes to scheduling priorities

Peter Peresini pointed out that the check for t >= 1 was
nonsense.  It was *supposed* to be an early-out for
priority==1, which it now is.

In the process of fixing that, I noticed that it looked
like the priority check was backwards and like a slightly
different check on the ready list would also make sense.
openflow: Better defaults for queue_stats_request

The port and queue to be queried used to default to 0, but
are now the more sensible "ALL" values.
openflow.nicira: header_only pack for nxm_entries

It use useful in some cases to be able to pack only the
header of an nxm_entry.  This is now supported.

This also fixes a bug that kept nx_reg_load actions
from working.

Thanks to Saul St. John for pointing out the issue.
openflow.nicira: Fix _eq in nx_reg_load

This was doing a bad job for checking equality of
nx_reg_load actions.
openflow_topology: fix xid_generator
nicira.py: add nx_reg_move
nicira.py add nx_output_reg
Merge pull request #53 from sstjohn/for-murphy

PR: Add nx output_reg and reg_move; topo fix

Primarily, this adds nx_reg_move and nx_output_reg actions.
Secondarily, it fixes a misnamed variable in the OpenFlowSwitch topology class.
nx: Minor cleanup

This mostly adds some newlines and makes nxm_entry's __repr__ its __str__.
nx: Add placeholder _nxm_ipv6 class

This class is currently a mangled version of the IPv4 nxm type since
IPAddr6 isn't available in lib.addresses yet.
nx: Fix setting of value in _nxm_ip
nx: Fix setting of nxm masks in __init__
nx: Fix and improve asserts in nxm unpack_new

The data length assertion was just wrong.  Also added a mask length assert.
nx: Fix unpack_new for masked nxm_entrys
nx: Fix typo in _eq() methods
nx: Fix unpacking of register actions

This also refactors some related stuff and adds the _class_for_nxm_header
function.
tests: Add tests for openflow.nicira
libopenflow: Refactor __ne__ methods

These were all identical (just negating __eq__), so they've been factored
out into the ofp_base superclass.
libopenflow: Clean up ofp_phy_port a bit

This had some literals that should be symbolic constants, and the
_validate() wasn't entirely sensible.
of_json: Fix regression with actions

While cleaning up libopenflow actions in 4378bea837, I changed
an "internal API" which broke of_json.  Fixed.

Thanks to faizul bari for pointing it out.