Bug 1259514 - Add manifestparser and reftest to Python search path; r=chmanchester

mozbuild Python changes to test manifest processing introduced these
dependencies.

DONTBUILD (NPOTB)

MozReview-Commit-ID: 9nT3G7qt988

--HG--
extra : rebase_source : d7d560477249a8e20a162d49faea85d4a49fe113

tools/docs/conf.py

@@ -15,11 +15,13 @@ OUR_DIR = os.path.dirname(__file__)
 topsrcdir = os.path.normpath(os.path.join(OUR_DIR, '..', '..'))
 
 EXTRA_PATHS = (
+    'layout/tools/reftest',
     'python/futures',
     'python/jsmin',
     'python/mach',
     'python/mozbuild',
     'python/which',
+    'testing/mozbase/manifestparser',
     'testing/mozbase/mozfile',
     'testing/mozbase/mozprocess',
 )