xrep/xreq don't belong in constant_names
Add TOS packet priority socket option
add 4.1.0 socket section

ROUTER_HANDOVER, TOS to start
setup constants with ROUTER_HANDOVER
Merge pull request #447 from claws/add_tos

closes #447
Install libsodium to run tests with curve feature
switch to ppa
Merge pull request #452 from ticosax/run-curve-tests

Install libsodium to run tests with curve feature