We want to disallow using unconfirmed outputs by default, so making the
default 1 confirmation seems a good idea. This also matches `bitcoind`s
minimum confirmation requirement.
Arming however breaks some of our tests, so I used `minconf=0` for the
breaking tests and added a new test specifically for the `minconf` parameter
for `fundchannel`.
Signed-off-by: Christian Decker <decker.christian@gmail.com>