Make housekeeping interval dynamic, fist signal is resource usage.

If no resources are used by the container since the last housekeeping,
we double the housekeeping interval until --max_housekeeping_interval.
If usage was detected, we drop it back to the baseline
(--housekeeping_interval).

From my tests this reduces CPU usage in CoreOS from ~8% to ~3% with no
real loss of accuracy.

Fixes #159
Cleanup graph JS and don't show values below 0.
Merge pull request #228 from vmarmol/update-libcontainer

Updating libcontainer version.
Adding the pprof HTTP service to cAdvisor.

This does not consume any resources unless the resources are queried.
Merge pull request #229 from vmarmol/pprof

Adding the pprof HTTP service to cAdvisor.
Merge pull request #227 from vmarmol/ui2

Cleanup graph JS and don't show values below 0.
Merge pull request #223 from vmarmol/dynamic-housekeeping

Make housekeeping interval dynamic, fist signal is resource usage.
Removing sampling and percentiles from interface.

Also removing all implementations.
Merge pull request #233 from vmarmol/master

Removing sampling and percentiles from interface.
Remove remaining parts of samples and percentiles.
Remove unused file.
Merge pull request #234 from vmarmol/obs

Remove unused file
Make dynamic housekeeping flag configurable
Merge pull request #237 from vmarmol/dyn

Make dynamic housekeeping flag configurable
Merge pull request #235 from vmarmol/rm

Remove remaining parts of samples and percentiles.
Adding all dependencies to Godeps.
Merge pull request #239 from vmarmol/deps

Adding all dependencies to Godeps.
Use inotify to watch for new containers.

This reduces cAdvisor CPU usage below 1% in my CoreOS system.

We also reduce global housekeeping to every 60s as a fallback in case we
miss an event.
Remove unused filter ContainerHandlers.
Wording changes to SubcontainerEvent comments