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.

web/pgadmin/utils/driver/psycopg2/__init__.py

@@ -155,7 +155,7 @@ SET bytea_output=escape;
 
             if status:
                 mgr.ver = res
-                mgr.sversion = int(pg_conn.server_version)
+                mgr.sversion = pg_conn.server_version
             else:
                 self.conn.close()
                 self.conn = None
@@ -178,13 +178,10 @@ WHERE db.datname = current_database()""")
         if 'password' in kwargs:
             mgr.password = kwargs['password']
 
-        if 'modules' in kwargs and isinstance(kwargs['modules'], list):
-            for m in sorted(
-                    kwargs['modules'], key=lambda module: module.priority
-                    ):
-                if m.instanceOf(mgr.ver):
-                    mgr.server_type = m.type
-                    mgr.module = m
+        if 'server_types' in kwargs and isinstance(kwargs['server_types'], list):
+            for st in kwargs['server_types']:
+                if st.instanceOf(mgr.ver):
+                    mgr.server_type = st.stype
                     break
 
         return True, None
@@ -380,9 +377,6 @@ class ServerManager(object):
     And, acts as connection manager for that particular session.
     """
     def __init__(self, server):
-        self.module = None
-        self.ver = None
-        self.sversion = None
         self.connections = dict()
 
         self.update(server)
@@ -394,10 +388,10 @@ class ServerManager(object):
         self.module = None
         self.ver = None
         self.sversion = None
+        self.server_type = None
         self.password = None
 
         self.sid = server.id
-        self.stype = None
         self.host = server.host
         self.port = server.port
         self.db = server.maintenance_db