New FairRoot patch release v-15.07a

There is the new FairRoot patch release v-15.07a available. Detailed information about this patch release can be found at

https://github.com/FairRootGroup/FairRoot/releases/tag/v-15.07a

An upgrade of the FairRoot version is only needed for users which either want to test with ROOT6 or need to compile FairRoot with gcc 5.x.