linux: Update to 3.13.7
grsecurity: Update stable and test patches

stable: 3.0-3.2.55-201403202347 -> 3.0-3.2.55-201403252026
test:   3.0-3.13.6-201403202349 -> 3.0-3.13.7-201403252047
grsecurity: Add myself as a maintainer