[CRIU] Add configuration file support for RPC

[Adrian Reber]

This adds support for the configuration files also to the RPC
code paths.

The main changes to support configuration files in CRIU's RPC mode is to
move the jump to RPC after configuration file parsing and to track which
options have been changed by the configuration files.

The reason for tracking which configuration options have changed is to
differentiate between an option having a default value and an option
having been set to the default value by the user via configuration
files.

If the users sets any option it is now overriding the RPC options and
the user can change CRIU's behavior when running via RPC.

		Adrian