Migrate from LZW::Revolunet to Compress::Bzip2

Migrate to Compress::Bzip2 from LZW::Revolunet at Pheix::Model::Database::Compression.

 NB:  It's dependent on:

1. Smart contract implementation (pheix-research/smart-contracts#38);
2. Middle level funcs return types (Str to Blob): 1, 2, 3, 4, etc...;
3. raw_pg method form Pheix::View::Pages;
4. convert-to-filechain.bash helper script;
5.  TBA .