We now removed the need for Boost:chrono in all the libs, to avoid
accidentally linking to it again this change makes the apps link to
the actual specific libs instead of just all.
Duplicate the test_bitcoin file into the common dir,
I hope to remove the original in future.
Make the common dir a new static lib and create a new
qtestlib based unit test out of the old doublespend unit test.
The old was based on levelDB which has scalability issues and stability
issues. (most often cited problem is corrupted database..)
This unspent output database I wrote is based on the idea that we need
never actually update any rows, which makes most old fashioned databases
a bad fit.
All we do is create rows and we forget rows. So lets design a DB to fit
that pattern.