Improve to ImageCacheManager
Merge branch 'master' of https://github.com/UnaCloud/unacloudIaaS2.0.git

Conflicts:
	unacloudIaaS2.0/grails-app/controllers/unacloudservices/WebServicesController.groovy
	unacloudIaaS2.0/grails-app/services/back/allocators/PhysicalMachineAllocatorService.groovy
	unacloudIaaS2.0/grails-app/services/unacloud2/WebServicesService.groovy
a