Revert "Server: Add min/max values"

This reverts commit 212595dcbbddfe6a9ebf35d646036302878d4362.
App: Fix a bug on low memory

Now the app does not try to clear the graphs if they don't exist.
Add push notification support

This uses an app-engine app. I will release source for that shortly,
right now it's pretty ugly and I want to tidy it up.
App: Minor bug fixes
Clean up a useless comment