Initial work in implementing a Bitcoin Currency

Through the new openclerk/currencies interfaces
Add Component test for all of Openclerk
Generate Currencies components with complex mappings

Updates to soundasleep/component-discovery allows us to
define more static methods to retrieve lists of things.
Work on moving crypto.php to Currencies functionality

We are starting with Bitcoin for now, things that are next:
- get_blockchain_wizard_config()
- account_data_grouped()
- external APIs
- maybe rewriting jobs framework so 'blockchain' is instead 'address'
  (arg=btc) job
Add safe_include_arg() helper function
Continuing work on Bitcoin Currency implementation

Moving all 'explorer' jobs to instead use 'address_CUR' job_type

Moving AllMigrations into \Migrations namespace

crypto.php can now load discovered currencies as necessary

bitcoin.png and blockchain.png are now provided by Core/Bitcoin
Fix failing tests
Remove unnecessary duplicated tests
Merge branch 'master' of https://github.com/soundasleep/openclerk