Monitor config set postgresql.pg_ctl bug fix

[rheaton]

• removes double-reload of config file during config set
• errors out when attempting to update to an invalid pg_ctl
• allows update to an invalid pg_ctl, in case the binary moved
• testing, minor update to test suite for error-handling

Note: this expects issue #742 to be fixed with PR #811 Without that fix, the test will error our with the semaphore issue.

Re-opening #816 because github is being odd

Co-authored-by: Jacob Champion pchampion@vmware.com

[rheaton]

@DimCitus Wanted to let you know that I'm out of office next week, but will be back Oct 18, if you have any comments. :)