Bug 214204 Only document content in document folder should be removed.[0601]
Description: Only document related content in document folder should be removed. Build number:2.3.0.v20080103 Steps to reproduce: 1. Deploy BIRT. 2. Edit web.xml to set BIRT_VIEWER_DOCUMENT_FOLDER to your local path and there are content inside the path. 3. Start server and click View Example to preview sample report. Expected result: Only content created by viewer should be removed in specified document folder. Actual result: All contents are deleted despite whether they are related with BIRT. Error log:n/a
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
* if the PARAM_INSTANCEID parameter in the url is not null, then return
	 * true to render the reportlet.
	 * 
	 * @param request
	 * @return true for render the reprtlet based on the instance id.
	 */
	public static boolean isIidReportlet( HttpServletRequest request )
	{
		String instanceId = getParameter( request, PARAM_INSTANCEID );
		return instanceId != null && instanceId.length( ) > 0;
	}
	/**
	 * Check whether the viewer allows master page content or not.
	 * 
	 * @param request
	 * @return
	 */
	public static boolean isMasterPageContent( HttpServletRequest request )
	{
		boolean isMasterPageContent = true;
		if ( "false".equalsIgnoreCase( getParameter( request, PARAM_MASTERPAGE ) ) ) 
		{
			isMasterPageContent = false;
		}
		return isMasterPageContent;
	}
	/**
	 * Check whether report design will overwrite report doc or not.
	 * 
	 * @param request