SAMtools with foss-2014b and zlib 1.2.8

It seems to be recommended with bump the zlib version and it already exists for both toolchains.

Also, I think it makes mroe sense moving forward with foss-2014b

bumped the version in intel-2014b as well.
downgrade to 1.2.7, to stay in sync with the existing SAMtools v1.1 easyconfig?