Merge pull request #62 from ivangayton/master

Changed "from pyxform import constants" to "import constants" in survey.py

pyxform/survey.py

@@ -9,7 +9,7 @@
 from odk_validate import check_xform
 from survey_element import SurveyElement
 from errors import PyXFormError
-from pyxform import constants
+import constants
 
 
 nsmap = {