Merge pull request #638 from smuzaffar/IB/CMSSW_7_0_X/stable

disable coral sub-package
Merge pull request #642 from smuzaffar/IB/CMSSW_7_0_X/stable

updated scram version to V2_2_5_pre7 to avoid perl module dependency
updated scram version to V2_2_5_pre8 which now prints only warning for scram_arch/os mismatch