Add first functionality to display profiling data in the web interface

* a servlet for providing profiling events
* an html page to profile the events
* an ajax call to load the data from the servlet
[FLINK-964] Draw InstanceSummaryProfilingEvents with flot as line charts (prototype)
[FLINK-964] generalize resource usage JS scripts, style charts
[FLINK-964] tear apart core plotting code and configuration
[FLINK-964] add support for SingleInstanceProfilingEvents (2 versions)
[FLINK-964] Clean-up prototype

* move summary profiling to the dashboard
* keep only one detailed resource usage page (the other page still exists, though)
* allow to modify the displayed time window in the flink-conf.yaml
[FLINK-964] Changes according to code review

* profiling is disable by default
* the plots on the index page and the link to the detailed resource usage page are only shown when profiling is enabled
* remove a backup file
Merge branch 'FLINK-964' of https://github.com/sekruse/incubator-flink into FLINK-964