Added missing crawler spec file identifiers to 'crawler.properties'
com.openexchange.subscribe.crawler.gmx.de=true
com.openexchange.subscribe.crawler.yahoocom=true
com.openexchange.subscribe.crawler.web.de=true
com.openexchange.subscribe.crawler.gmx.de=true
com.openexchange.subscribe.crawler.yahoocom=true
com.openexchange.subscribe.crawler.web.de=true