DSA SSH keys say "dss" in them, not "dsa".
Merge pull request #187 from mlc/dsa_key_fix

DSA SSH keys say "dss" in them, not "dsa".
Remove and create cerowrt/files dir to fix first time run
Added build instructions, cleaned up System overview
README updates

Indicate that only the leftmost front button works for failsafe (fixes #193), remove HOPE references.