Update test_dot.py to fix encoding error with Python2.7
Update test_dot.py to fix encoding error with Python2.7

test_unifying (prov.tests.test_model.TestUnification) ... ok

======================================================================
ERROR: test_all_examples (prov.tests.test_dot.SVGDotOutputTest)
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Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/prov/tests/test_model.py", line 39, in test_all_examples
    self.do_tests(g)
  File "/<<PKGBUILDDIR>>/prov/tests/test_dot.py", line 28, in do_tests
    svg_content = dot.create(format="svg")
  File "/usr/lib/python2.7/dist-packages/pydot.py", line 1836, in create
    self.write(tmp_name, encoding=encoding)
  File "/usr/lib/python2.7/dist-packages/pydot.py", line 1754, in write
    f.write(s)
UnicodeEncodeError: 'ascii' codec can't encode character u'\u1ef3' in position 1489: ordinal not in range(128)
trungdong/prov