Fix double quotes, add omprog send mail example

[paulfertser]

omprog: add example script to run an app for each message

This adds a simple POSIX shell script that can be used to execute an
program for every log message (as the legacy ^ action).

Since the example shows how to use it to send mail, a reference is added
to the ommail page too.

[paulfertser]

The build failed probably because it tried to fetch too early? I do not see how I can retrigger it.