Update contrib/gitian-descriptors/* for use by blackcoin

Signed-off-by: Xerxes Rånby <xerxes@gudinna.com>
[wallet] Consider generated coins mature at COINBASE_MATURITY+1

We're not seeing large reorgs that would justify waiting a large
 amount past the rule required maturity, and the extra three
 hours is just a nuisance. Take one more block to at least give
 the 100th block time to propagate.

Conflicts:
	src/main.cpp
Merge branch 'gitian' of https://github.com/xranby/blackcoin