Restructure, logging, initial systemd support, pre/post network scripts

[vholer]

Changes include:

• repository code restructure, code moved into src/ and files are tagged (e.g. scripts##systemd.rpm)
• EL6 (SysV) and EL7 (Systemd) support, Debian/Ubuntu work like before (needs to be fixed)
• packages have dependencies
• pre/post networking contextualization scripts
• runtime and state files moved into /var/run/one-context (context, one_env, scripts)
• better hotplug handling on systemd/KVM
• main script logs via journald/logger

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Debian/Ubuntu need to be fixed same way as ELs, but sometimes later as a separate PR. TODO:

• systemd support
• pre/post networking scripts for SysV