Add question type: phone number (#1462)

* Add Phonenumber-Field as to Questions

* Add setup requirements

* Add list of ask-during-checkin restricted question types and enforce it

* Fix requirements

* Fix crash using custom locales

* Re-format phone numbers when outputting to humans

* Initialize country code field with a guess for the customer's country

* Document TEL type in API docs

src/setup.py

@@ -146,6 +146,8 @@ setup(
         'django-oauth-toolkit==1.2.*',
         'oauthlib==2.1.*',
         'urllib3==1.24.*',  # required by current requests
+        'django-phonenumber-field==3.0.*',
+        'phonenumberslite==8.10.*',
     ],
     extras_require={
         'dev': [