Collapsible implementation - initial implementation.
Add events.
Add expand/collapse icons.
Add expand/collapse classes to the collapsible panel.
Add animation
Fix typo.
Add resizing functionality
Fix content height detection on iOS.
Code refactoring
Add km-plus and km-minus icons
Add collapsible widget styles
Add collapsible widget to kendo.ui.core
Merge branch 'collapsible-panel' into core-master