pgAdmin 4 commit: [Configuration][Migration] Use 'alembic' for migratio

[Configuration][Migration] Use 'alembic' for migration of the SQLite
based configuration file from one version to another, and also allows us
to have a single path of creating the table instead of creating tables
using SQLAlchemy or hand rolled SQL

This allows us to run the migrations directly in the code, and it will
avoid the error prone version numbering.

Patched by: Sarah McAlear
Revisions: Joao Pedro De Almeida Pereira, George Gelashvili.
Reviewed by: Ashesh Vashi, Murtuza Zabuawala

Branch
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master

Details
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https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=6283ef7f5e4379d5e2202ca2919b9ea76caf57c7
Author: Sarah McAlear <smcalear(at)pivotal(dot)io>

Modified Files
--------------
README | 16 ++
web/migrations/alembic.ini | 54 ++++
web/migrations/env.py | 94 +++++++
web/migrations/script.py.mako | 33 +++
web/migrations/versions/09d53fca90c7_.py | 242 +++++++++++++++++
web/migrations/versions/fdc58d9bd449_.py | 128 +++++++++
web/pgAdmin4.py | 11 -
web/pgAdmin4.wsgi | 20 ++
web/pgadmin/__init__.py | 42 +--
web/pgadmin/setup/__init__.py | 13 +
web/pgadmin/setup/data_directory.py | 32 +++
web/pgadmin/setup/db_upgrade.py | 25 ++
web/pgadmin/setup/db_version.py | 28 ++
web/pgadmin/setup/user_info.py | 72 +++++
web/setup.py | 439 +------------------------------
15 files changed, 779 insertions(+), 470 deletions(-)