Load from directory support. Bug fixes

hive/indexer/mock_block_provider.py

hive/indexer/mock_data_provider.py

hive/indexer/mock_vops_provider.py

hive/indexer/sync.py

hive/steem/client.py

...data/examples/block_data/mock_block_data_example_001.json

...data/examples/block_data/mock_block_data_example_002.json

mock_data/examples/vops_data/mock_vops_data_example_001.json

mock_data/examples/vops_data/mock_vops_data_example_002.json