Open up Django compatibility and remove outdated Travis tests

Update "Django>=1.8,<=2.2" to "Django>=1.8,<=3.1" #81

Fix Travis tests

#80 Add user permissions for elastic search

fix twine check err and add coverage for es_list

• fix #59 twine check error in 0.8.1
• fix #50 add test coverage for es_list
• fix #58 ignore indexes with a dot in name in es_list --es-only and es_dangerous_reset

Increase test coverage for es_list and ignore hidden es indexes

• fix #50 add test coverage for es_list
• fix #58 ignore indexes with a dot in name in es_list --es-only and es_dangerous_reset

Add support for Django 1.10, 1.11, 2.0, 2.1, drop support for Python 2

• fix #6 support Django 2
• fix #43 remove es_deactivate
• fix #44 add django 1.10 and 1.11 to test matrix
• fix #45 remove support for python 2
• In practice, Python 2 may work, but it is removed from the test matrix and won't be updated

Update Dev Dependencies and Release on PyPI

• See #7 Convert Readme to rst for pypi

fix #41 stack trace when indexing in py3

fix #41 stack trace when indexing in py3

fix es_update --start

• fix #36 es_update --start flag broken

fix #35 open multiprocessing log in context handler

• fix #35 open multiprocessing log in context handler

fix #33 error when nothing to resume using --resume

Only ticket: #33 error when nothing to resume using --resume