INTEG-181: XSS vulnerability on Quick Search box

Fix description:
	- Escape HTML script by XSSUtils implemented in COMMONS-312 before rendering
INTEG-288: "Description" field in Metadata has XSS vulnerability in Activity Stream

Fix description:
  - Escape XSS character of description when rendering in the Activity Stream
INTEG-291: [Activity Stream] Incorrect thumbnail image of Powerpoint files shared via Activity Composer

Problem analysis:
* Powerpoint files are recognized as normal file without thumbnail view support.

Fix description:
* Use ECMS method to check whether the MIME type supports thumbnail view.