pytables: fix rpath for hdf5

Previously it was giving:

In [1]: import tables
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-1-389ecae14f10> in <module>()
----> 1 import tables

/nobackup/certik/python-hpcmp2/opt/profile/ceic/lib/python2.7/site-packages/tables/__init__.py in <module>()
     28
     29 # Necessary imports to get versions stored on the Pyrex extension
---> 30 from tables.utilsExtension import getPyTablesVersion, getHDF5Version
     31
     32

ImportError: libhdf5.so.8: cannot open shared object file: No such file or directory

Now it works:

In [1]: import tables

In [2]: