Building Bitcoin Vault

See doc/build-*.md for instructions on building the various elements of this reference implementation of Bitcoin Vault.

Changes from Bitcoin Core

Bitcoin Core	Bitcoin Vault
`bitcoin.conf`	`bvault.conf`
`~/.bitcoin`	`~/.bvault`
`~/Library/Application Support/Bitcoin`	`~/Library/Application Support/BitcoinVault`
`C:\Documents and Settings\Username\Application Data\Bitcoin`	`C:\Documents and Settings\Username\Application Data\BitcoinVault`