pgAdmin 4 commit: Initial cut at saving/retrieving the main browser lay

Initial cut at saving/retrieving the main browser layout.
Still needs some work to:

- Minimise AJAX calls by writing multiple settings at once.
- Move the settings storage/retrieval JS code into a global file
- Avoid using synchronous AJAX calls in the main thread

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=e9951040003c9b699fa2f028409976a0ec19484a

Modified Files
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web/pgadmin/browser/templates/browser/body.html |  106 ++++++++++++++++-------
web/pgadmin/settings/__init__.py                |   37 ++++++++
web/pgadmin/settings/settings_model.py          |   47 ++++++++++
web/pgadmin/settings/views.py                   |   50 +++++++++++
web/pgadmin/templates/base.html                 |    1 +
web/pgadmin/utils/views.py                      |    1 -
web/settings/__init__.py                        |   79 -----------------
web/settings/settings_model.py                  |   49 -----------
web/setup.py                                    |    2 +-
9 files changed, 211 insertions(+), 161 deletions(-)