Fixes around post data edit

See merge request !120

Fixed edit case with empty title, body or json_metadata
Fixed use of json - now everywhere ujson is used
In case json_metadata in comment_operation would not actually be json, HiveMind no longer crashes on access
Since we are handling bad json anyway it was no longer needed to fill empty json_metadata with {}, original empty string restored

Avoiding a redundant loop during `effective_comment_vote_operation` processing

See merge request !116

Teh call `get_profile` works

See merge request !110

Some characters apparently need long 8-byte encoding

See merge request !117

[ABW]: some characters apparently need long 8-byte encoding (problem actually caused by use of ujson)

Unified some error messages and added CI groups for tests made in new scheme

See merge request !114

added new test groups to CI with at least single test to make it easier to move tests accourding to new scheme (only follow/tags have no negative tests so no such groups were added)

Database api fixes

See merge request !103

fixed unicode escaping

See merge request !113

[ABW]: added separate tests to CI (all tests will eventually be run through folders instead of common .yaml file)

Add num_block to tables, add proper reblog support

See merge request !112

tests/tests_api submodule changed to introduce get_discussions_by_blog testcases.

See merge request !111

* Added num_block to hive_follow and hive_reblog tables,
* Added reblog class to process reblog operations,
* Sync will now show version info, git revision and db version on start

Eliminated obsolete columns from hive_posts: author_rep, url, root_title

See merge request !109

Simplified hive_votes definition: PK changed to triple [author_id, permlink_id, voter_id], eliminated id column since votes are not referenced
Removed some indexes from hive_votes (redundant)

- Indexes are rebuilt only when resumed sync process imported enough number of blocks.

See merge request !108

- After-initial-sync updates are constrained to the number of blocks currently processed.

Fixes on deleted posts and beneficiaries

See merge request !105

[ABW]: Deleted posts filtered out from hive_posts_view, no longer need filtering everywhere outside (also fixes some places where check on deleted post was missing).
sqlalchemy has problem with passing JSON to query parameter - changed to passing as string (fixes problem of {} where [] should be).

List comments by parent opts

See merge request !104

Various small fixes in bridge and condenser api

See merge request !102

Fixed code that reads beneficiaries from operation
Changed error response from None to proper error in bridge.get_profile and bridge.get_post_header
Empty raw_json in hive_accounts no longer crashes API calls
condenser_api uses sum of payout and pending_payout for correct order by payout
When selecting blog posts with special start_index value (0 or -1) limit is shortened when there is not enough posts (was error which made no sense)
[Ign] changed order in hive_posts_view so all vote related fields are near each other