Implements #1211
Fix org.zkoss.zel.ELException: Error writing 'crawlScope' on type com.jaeksoft.searchlib.web.controller.runtime.CrawlCacheComposer
>>com.jaeksoft.searchlib.SearchLibException: java.io.IOException: The folder /var/local/crawl-cache/... does not exists
Merge pull request #1215 from emmanuel-keller/1.6

Bug fix and improvement