toaster: enhancements for the startup sequence

toaster: enhancements for the startup sequence

This patch brings fixes and enhancements in the startup sequence.

- the dependency version checking is now correctly enforced when
starting in both modes
- fixed errors in looking up environment variables
- added message with 'daemon' program start location
- presenting menu for selecting config file

[YOCTO #7283]
[YOCTO #7291]
[YOCTO #7273]

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>