+ implement scenery of downloading file
+ IO Storage interface + in memory implementation
+ add FileDownloader class to hide interaction with callbacks
+ PlotRepresentation know what metricNode it represented
+ implement idea - one MetricNode = one PlotSeriesDto
- plot id is needed only for markings that are not really needed in current implementation
+ download file without pop up new window
+ Download service
+ ability to save trends as csv plots
+ csv file generator : flush / close in finally block
- remove useless methods from ControlTree class
+ more meaningful messages, log error on exception while cvs file creation
+ rename InMemoryNewFileStorage -> InMemoryFileStorage
-- truncate file storage implementation by decision of jagger team as useless for current task and complicated
Merge branch 'master' of github.com:griddynamics/jagger into download-servlet

Conflicts:
	webclient/src/main/java/com/griddynamics/jagger/webclient/client/components/PlotsPanel.java
	webclient/src/main/java/com/griddynamics/jagger/webclient/client/trends/Trends.java
+ little changes (bad merge)
Merge pull request #523 from amikryukov/download-servlet

JFG-767 Create package for CSV export. Implement exporting of plots