`swissknife check` ensures empty clg mountpoints
Merge pull request #516 from reneme/fix-non_empty_nested

`swissknife check` Ensures That Nested Catalog Mountpoints are Empty
add get_partition_for_path()
add check for hazardous AUFS config
print warning on harzardous AUFS config
take AUFS release over kernel version if possible
descriptive comments for find_hazardous_aufs_config()
add link to workaround page on cernvm.cern.ch
check release number in aufs_type.h
run health check after mkfs
generalize regex for AUFS_VERSION
explanatory comments
list of possible aufs_type.h locations
TEST: AUFS warning for potential kernel deadlock
build a debug version of cvmfs_unittests
add relaxed matching to pathspec
TEST: unit test relaxed matching
relaxed matching for negative dirtab rules
TEST: T_Dirtab.MultiDirectoryWildcardsInNegativeRules
Refactor: remove code duplication