Most of the logic to build a transaction that sends coin to
another party. Still requires more debugging and clean up.
Main changes and additions are:
* Update to serde 1.0
* API endpoint to retrieve an Output
* Output is now Serialize and Deserialize
* Wallet configuration
* Command line for the send operation
* Wallet data checker to update created outputs into confirmed
* Wallet-specific configuration
Allows for custom operations associated with POST requests under
the main resource path. For example, in addition to POST on /user
to create a user, allow easy support for /user/login and
/user/logout.
