Make custom deriva.core.urlquote work for unicode names in py2 and py3
Make custom deriva.core.urlquote work for unicode names in py2 and py3

The previous version would fail on py2 because urlquote could not
encode the non-8bit code-points.  Calling encode('utf-8') explicitly
will do the right thing on both py2 and py3 without writing any
non-portable code here...

informatics-isi-edu/deriva-py