PATCH: RM# 1679 - Background process for "restore" not reporting status back to pgAdmin

Hi Dave,

Please find the patch to resolve the issue reported in RM #1679
<https://redmine.postgresql.org/issues/1679>

This will take care of:
- Find the appropriate available Python interpreter to execute the
process_executor.py.
In case of WSGI or Runtime, it was not properly find the interpreter
required to execute that script. Also, on windows - we should give priority
to the windowless python interpreter (if available).
- Execute the process_executor.py script with proper platform dependent
flags to run it as daemon.
- Run the process_executor.py in proper daemon mode. It helps to run the
long running processes like backup, restore, etc.
On windows, run the process_executor.py from process_executor.py in
detached mode to allow the child process to run in detached mode.
On POSIX, fork the process_executor.py to allow the child process to run
in daemon mode.
Also - listen the signal like SIGINT, SIGTERM, so that - the child does
not kill, or hangup (It used to happen.

NOTE:
This patch does not take care of the unicode errors in the path. I will
send a separate patch for the same.

--

Thanks & Regards,

Ashesh Vashi
EnterpriseDB INDIA: Enterprise PostgreSQL Company
<http://www.enterprisedb.com>

*http://www.linkedin.com/in/asheshvashi*
<http://www.linkedin.com/in/asheshvashi>