Disk utilization

Add method to update array of values for each disk
Add method to calculate top disks for selected attrs
Add method to render partition layout for top disks
Disk utilization

Update disk bars width dynamically, and handle resize.
Merge branch 'master' into issue#217_disk_widget
Disk utilization

Render disk activity only if widget is maximized
Disk activity

Change samples to 600, and frequency to 1 sec
Display reads_completed and writes_completed
Disk utilization

Display data read/written
Disk utilization

Add tick formatter for time on x axis for graphs
Add wrapper div for graphs so that resize can empty the wrapper div, so
that legends are removed properly.
Disk utilization

Set selected disk
Disk utilization

Set handler for disk select, dont use events since it overrides base
class events.
Disk utilization

Display no activity msg if there is no disk activity
Create color scale
Add handler for sort attr selection
Disk utilization

Show total and percentage attribute values for top disks
Merge pull request #279 from sujeetsr/issue#217_disk_widget

Issue#217 disk widget