pgAdmin 4 commit: Browser window was not closing - Fixed.

Browser window was not closing - Fixed.
App should quit on all windows closed.
Added linter config from pgadmin and fixed linter issues.
Other cleanup.

Branch
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electron2

Details
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https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=551bf9459faf679977f5673dcc901cdd5ecee1de

Modified Files
--------------
electron/.eslintrc              |   47 --
electron/.eslintrc.js           |   54 ++
electron/package.json           |    4 +-
electron/pgadmin.js             |   60 ---
electron/src/configure_store.js |   12 +-
electron/src/configure_ui.html  |    8 +-
electron/src/configure_ui.js    |   49 +-
electron/src/index.js           |   78 +--
electron/yarn.lock              | 1103 +++++++++++++++++++++++++++++++--------
9 files changed, 1013 insertions(+), 402 deletions(-)