Demo mode allows users to clear logged data

[Myles Metzler]

The demo works better if there is actually data in the system, prevent "demo" admins from removing this data.

[Myles Metzler]

addresses #84 (demo mode allows log delete)

→ <<cset 483016dfd9ad>>

[Myles Metzler]

Merged in dev-bugfix (pull request #4)

fixes #80 (default configuration pages fails loading) fixes #81 (w/ no log data; recent query fails) fixes #82 (w/ no log data; trend stats request fails) fixes #84 (demo mode allows log delete) fixes #85 (needed let causing issues with older browsers)

Approved-by: Myles Metzler [e-mail]

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