Dealing with globbed paths should recursively call "isDirectory/listStatus"

[fnothaft]

In ADAMContext, we have code that loads metadata from underneath globbed paths. However, you need to glob inside the directory for this to work (i.e., instead of globbing "all_my_reads_.adam", you'd glob "all_my_reads_.adam/*). We could fix this by following all globStatus/listStatus calls with a check whether the file is a directory, and calling listStatus if it is a directory.