Cast all follow name data to string. Should protect against setting non string data types as names in follower and following

Removed delta calculations from follow.py. Follower/following calculation moved to dedicated SQL function.

[Fix] get_account_reputations no longer fails with error when account_lower_bound is skipped; also added real default value for limit (1000)
[Fix] bridge_get_ranked_post_by_trends_for_observer_communities now validates observer like other functions of the same family
[Fix] all VOLATILE get_ranked_post related SQL functions turned into STABLE

Merge branch 'vote_muting_and_other_small_fixes' of gitlab.syncad.com:hive/hivemind into vote_muting_and_other_small_fixes

Vote muting and other small fixes

See merge request !371

Follower and following names validation and type check

See merge request !364

bridge_api.get_account_posts "by comment" optimization.

See merge request !373

Resolve "Url of submodule should be relative on Gitlab server"

See merge request !376