pgAdmin 4 commit: Changed the logic to identify the PostgreSQL server v

Changed the logic to identify the PostgreSQL server variant, when we
connect to the database server. Also, added modified the way, we do
check the node is supported by the server.

Instead of creating separate blueprint for the server types, they will
be independently works. In order to add different variant of the
PostgreSQL, we need to extend the ServerType class, and override the
'instanceOf' function for identification using version string. Please
take a look at the ppas.py for the example.

During checking the back-end support for the node, we will also check
the server type (variant) along with the version within the range of
maximum and minimum version for the node. And, the same support added
for the schema attributes in front-end (JavaScript).

Really thankful to Khushboo Vashi for her initial work in front-end. I
took it further from there.

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=77834ccdda11e8aeecbc171de9b136a5a6179ed1

Modified Files
--------------
web/pgadmin/browser/__init__.py | 3 +-
web/pgadmin/browser/collection.py | 10 +-
web/pgadmin/browser/server_groups/__init__.py | 2 -
.../browser/server_groups/servers/PPAS/__init__.py | 44 ------
.../server_groups/servers/PPAS/static/img/ppas.png | Bin 676 -> 0 bytes
.../server_groups/servers/PostgreSQL/__init__.py | 43 ------
.../servers/PostgreSQL/static/img/pg.png | Bin 850 -> 0 bytes
.../browser/server_groups/servers/__init__.py | 148 +++-----------------
web/pgadmin/browser/server_groups/servers/ppas.py | 19 +++
.../server_groups/servers/static/img/pg.png | Bin 0 -> 850 bytes
.../server_groups/servers/static/img/ppas.png | Bin 0 -> 676 bytes
.../server_groups/servers/templates/css/node.css | 7 -
.../servers/templates/css/server_type.css | 7 +
.../servers/templates/servers/servers.js | 30 ++--
web/pgadmin/browser/server_groups/servers/types.py | 75 ++++++++++
.../browser/templates/browser/js/browser.js | 2 +-
.../browser/templates/browser/js/collection.js | 42 +++---
web/pgadmin/browser/templates/browser/js/node.js | 78 +++++++----
web/pgadmin/browser/utils.py | 38 +++--
web/pgadmin/static/js/backform.pgadmin.js | 83 ++++++-----
web/pgadmin/utils/driver/psycopg2/__init__.py | 18 +--
21 files changed, 307 insertions(+), 342 deletions(-)