Z-Eye Service: SNMP Community caching fixes. It's now working properly
Z-Eye service: switch backup uses SNMPCommunity cacher
* use SNMP community cache from the module
* wait when a caching process is in progress
Z-Eye service: oops forget to init variable
Z-Eye service: now all module which need z_eye_snmp_cache use SNMPCommunityCacher instead of db