Add xblock-utils requirement

requirements.txt

 -e .
 unicodecsv==0.9.4
 -e git://github.com/nosedjango/nosedjango.git@ed7d7f9aa969252ff799ec159f828eaa8c1cbc5a#egg=nosedjango-dev
+-e git://github.com/edx-solutions/xblock-utils.git#egg=xblock-utils

setup.py

@@ -70,7 +70,9 @@ setup(
     packages=['mentoring', 'mentoring.migrations'],
     install_requires=[
         'XBlock',
+        'xblock-utils',
     ],
+    dependency_links = ['http://github.com/edx-solutions/xblock-utils/tarball/master#egg=xblock-utils'],
     entry_points={
         'xblock.v1': BLOCKS,
         'xblock.light_children': BLOCKS_CHILDREN,