Move jar unpack dir into ice_root for all cases.

Fixed a shutdown cleanup problem where the directory would not get cleaned up unless
it was already empty.

Add a DeleteDirHandler class to recursively remove the h2o-temp-nnn jar unpack
directory on shutdown.

These changes caused some legacy hadoop code to stop building, so I deleted it.
Merge branch 'master' of github.com:0xdata/h2o