VM-alloc critical_applications

Paper: Problem formalization section updated

code: now also minimizing the number of VMs of the same tenant allocated to the same PM

code: program again fully functional, now with full support for VM groups of given size and reservations

Code: perl program being modified so that it can cope with changed input format

code: changed perl program to read the yml files of the new format

code: input format changed to add more support for VM replica groups as well as to more easily scale the input

Paper: split into multiple files

Code: added level_of_replication constraints

Code: added all CPU constraints

Paper: added section on linear program