Introduce CM_Process

- includes forking and keepalive functionality
Adjust process usages
Remove unused CM_Process_Fork
Reset children when spawning new process (+formatting)
Wrap clearing children and uninstalling handler for new child process into _reset() method
Exit 0 for INT/TERM
Merge branch 'master' of github.com:cargomedia/CM into issue-908
Merge fork and keepAlive option
Fix keepAlive condition
Fix conditions
Merge pull request #908 from tomaszdurka/issue-908

Introduce CM_Process (instead of CM_Process_Fork)