pgAdmin 4 commit: Backend changes to fetch the statistics for the datab

Backend changes to fetch the statistics for the database and server
nodes, along with the front-end changes for those node.

NOTE:
We've not yet added the support to show them on the front-end.

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=8a39b3a70047484adf875a6a19064d1c0e99e6d0

Modified Files
--------------
.../browser/server_groups/servers/__init__.py | 27 ++++++++++++-
.../server_groups/servers/databases/__init__.py | 47 +++++++++++++---------
.../databases/templates/databases/js/databases.js | 4 +-
.../templates/databases/sql/9.1_plus/nodes.sql | 6 ++-
.../databases/sql/9.1_plus/properties.sql | 14 +++----
.../templates/databases/sql/9.1_plus/stats.sql | 29 +++++++++----
.../templates/databases/sql/9.2_plus/nodes.sql | 10 +++--
.../databases/sql/9.2_plus/properties.sql | 12 +++---
.../templates/databases/sql/9.2_plus/stats.sql | 34 ++++++++++++----
.../templates/databases/sql/9.3_plus/nodes.sql | 8 ++--
.../databases/sql/9.3_plus/properties.sql | 12 +++---
.../templates/databases/sql/9.3_plus/stats.sql | 34 ++++++++++++----
.../servers/templates/servers/servers.js | 2 +
.../browser/templates/browser/js/collection.js | 11 ++++-
14 files changed, 179 insertions(+), 71 deletions(-)