add DEFAULT_UPNP constant in net

- as this is a shared Core/GUI setting, this makes it easier to keep them
  in sync (also no new includes are needed)
release: Bump the OSX SDK to 10.7 for gitian builds

This fixes the display on Retina Macbooks. It also moves us away from depending
on the ancient XCode3 sdk.
Merge pull request #4245

066d9a5 [Qt] Fix Start bitcoin on system login (Cozz Lovan)
Merge pull request #4132

d4e1c61 add DEFAULT_UPNP constant in net (Philip Kaufmann)
Merge pull request #4229

2869b13 release: Bump the OSX SDK to 10.7 for gitian builds (Cory Fields)
gitian: Add cfields to gitian download scripts
No references to centralized databases in help text.
Merge pull request #4251 from theuni/cfields-pgp

gitian: Add cfields to gitian download scripts
Fix name of Cory's pgp key
Merge pull request #4249

b5ef85c No references to centralized databases in help text. (Pieter Wuille)
Add vout to ListTransactions output