Refactored installation scripts. More in details.

* Check every significant command result in sofin-install
* Disabled forced failure on unsupported OSes.
* C++ compiler as a demand.
* Disabled SHC use (it was fun, but i'm serious now)
* Install default definitions for root only if not already there.

Signed-off-by: Daniel (dmilith) Dettlaff <dmilith@verknowsys.com>