logserver: Add dirWatcher to delete app logs above threshold and put data in influxDB.
logserver: Add dirWatcher to delete app logs above threshold and put data in influxDB.

dir watcher runs every 10 seconds (configurable). It does the following:
* Checks to see if an app's logs exceeds the specified log limit threshold. If it does then it deletes the oldest files till the app's space usage is below app_log_threshold - app_log_threshold_buffer.
* New encountered logs are reported to InfluxDB.

State of the logserver is also saved. This helps make sure that if the logserver is restarted then it does not report old logs as new ones to InfluxDB.

Also includes the following bug fixes:
* Moved the HTML writing logic out of the Readdir loop.
* Created separate sections so kept it out of the loop.
* skiamonitoring -> skiamonitor.com

BUG=skia:

Review URL: https://codereview.chromium.org/723263002

google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot