Bq-schema

* fix for abstract table feature: only ignoring direct descendants of ABC 27

v.0.6.2
* add flag for ignoring abstract tables when looking for schema diffs

* fix table finder script

* update google-bigquery client to version 2

* library know works with late evaluation of type annotations

* Add support for geography type

Improve the migration tool:
* Show all changes, do not abort after the first change
* Ask for confirmation before applying migrations