This removes the transaction-signing code from the hub internal codebase.
The only user for this was the API call signrawtransaction,
and a lot of unit testing code.
I'd argue that if the user needs to send a private key to the hub via
RPC for signing his transaction, then they are doing it wrong.
This also removes the duplicate test double_spend which tests
functionality also tested in the DoubleSpendProofTest.
As an aside, the flowee/utils library still has full signing capability
and we suggest using the TransactionBuilder API for that.
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.
These are technically static libs, but not in any way shared libs.
They are used solely only by this repo and really only by the hub.
Most important, no header files are installed and basically none of
the normal rules for reusable libraries are applied to these files.
tomFlowee