MNEMONIC-386: Improve the CentOS Dockerfile for http proxy mode
MNEMONIC-386: Improve the CentOS Dockerfile for http proxy mode

yzz127/incubator-mnemonic,yzz127/incubator-mnemonic,lql5083psu/incubator-mnemonic,lql5083psu/incubator-mnemonic,johnugeorge/incubator-mnemonic,yzz127/incubator-mnemonic,paleyss/incubator-mnemonic,lql5083psu/incubator-mnemonic,paleyss/incubator-mnemonic,johnugeorge/incubator-mnemonic,NonVolatileComputing/incubator-mnemonic,lql5083psu/incubator-mnemonic,yzz127/incubator-mnemonic,NonVolatileComputing/incubator-mnemonic,NonVolatileComputing/incubator-mnemonic,paleyss/incubator-mnemonic,paleyss/incubator-mnemonic,NonVolatileComputing/incubator-mnemonic,johnugeorge/incubator-mnemonic,johnugeorge/incubator-mnemonic