Update build dependencies for current Debian (wheezy) and Ubuntu (raring)

doc/readme-qt.txt's "apt-get install..." fails saying:
E: Package 'libdb4.8++-dev' has no installation candidate
but libdb++-dev exists and installs the latest version (5.1)

Building then fails saying:
src/net.cpp:20:32: fatal error: miniupnpc/miniwget.h: No such file or directory
compilation terminated.
for which the is to add libminiupnpc-dev