Cleanup/maintenance

[UdjinM6]

Few maintenance/cleanup commits grouped together:

• remove global instance references inside own classes
• better logging (a bit more verbose and a bit better structured in few cases)
• remove unused code (masternode budget was already replace by governance objects, custom data dump functions was generalized and replaced by falt-database)
• fix tabs/spaces
• bitcoin->dash
• fix README.md (12.1, travis badges, forum link)

Was split for easier review, can be squashed if needed.

[schinzelh]

ACK 0203103