Issue #372: indexer controlled by systemd

[MrBunsy]

• Red Hat happy systemd service file now included in repo.
• Daemon tidied up so it's now a single blocking thread
• Daemon class stripped of everything not necessary
• Admin pages tidied up so only indexer related function is now to restart indexer
• Remaining win32 support attempts stripped out.

--kill is still an option to the indexer script, it will create var/indexer.suicide which the indexer will detect and treat as an interrupt.