Version 0.0.8 released.

Changelog:

- add database migrations. This is tricky and may fail. In case, delete the storage and sync headers again (I hope not).
- improve the efficiency of SQLite DB (fewer calls, less size) by changing data serialization and queries. reduces the size by roughly a half.
- improve the efficiency on the P2P side when new block headers are notified (should fix race conditions of issue #85 )
- persist and index raw transactions when fetched via getblock (reduce network calls)
- improve the efficiency of the getblock verbose calls by using the per-block transactions index, avoid to load the entire block data
- increase the cache agent speed by using the per-block transactions index instead of the leveldb iterator

There are a lot of changes that may break the code, but they are very needed and useful.
The basic idea is to improve data indexing so that it can also be used in the future for other purposes (layerthree).
The release is available on pypi and docker hub.

Sources: https://github.com/gdassori/spruned/releases/tag/0.0.8
Pypi: https://pypi.org/project/spruned/
Dockerhub: https://hub.docker.com/r/gdassori/spruned