* New configuration keywords

** sigterm SIG

Available for use in "component" sections.  This statement defines
signal which pies should send to the running component instance in
order to terminate it.  Defaults to SIGTERM.

* Fix the component shutdown sequence

The shutdown sequence is determined taking into account dependencies
between components, so that all dependent components are stopped
before their prerequisite components.

* Fallback log file

Fallback log file is a place where pies writes out of band log messages,
i.e. messages about not being able to open syslog socket or send logs
to it.  Regular log messages are diverted to this file if syslog was
requested, but cannot be used because of a permanent error.

* Bugfixes

** Fix piesctl config reload

** Fix configuration preprocessing.

** Varios fixes in REST API server.