Introduce resource management/limits

[jakubsacha]

In order to limit resource (CPU) usage on the CI server, it would be beneficial to include a way to set up some limits.

The initial idea is to do it when we build docker-compose in the DockerComposeYamlBuilder:

        $composeConfig[$ciContainerName]['cpu_shares'] = 50;
        $composeConfig[$ciContainerName]['cpu_quota'] = '...';
        $composeConfig[$ciContainerName]['cpu_period'] = '...';

To consider:

• CPU quota depends on the CI server configuration (it's actually depending even on the node that the given job is executed). We should find a way to make intelligent.
• there is the nice description here:
  https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
  what we could do is to detect a number of CPU cores on the given machine and then limit cpu_quota to - let's say 95% of the CPU.
• we could also make it very static and allow a single job to use not more than the given percentage of the cores on the ci server.
• if the single stage is executing multiple concurrent jobs we should probably limit them even further to avoid a situation when we burn CPU heavily and that leads to unstable CI server.