Add testing for Django 2.1 (#127)

* Fix compatibility with pip 10+

* Fix Travis build failure on MacOS

Error: python 2.7.14 is already installed
To upgrade to 3.6.5, run `brew upgrade python`

* Add testing for Django 2.1

.travis.yml

@@ -40,6 +40,8 @@ matrix:
       env: DJANGO=1.11.*
     - python: 3.6
       env: DJANGO=2.0.*
+    - python: 3.6
+      env: DJANGO=2.1.*
 
     - os: osx
       language: generic
@@ -50,10 +52,8 @@ matrix:
 # system architecture, OSX tests will only run on one Python 3 + latest stable
 # release for Django.
 before_install:
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update                ; fi
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install python3       ; fi
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then virtualenv venv -p python3 ; fi
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then source venv/bin/activate   ; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then python3 -m venv env        ; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then source env/bin/activate    ; fi
 
 install:
   - python dev.py -no-container

README.rst

@@ -44,5 +44,5 @@ Preview
 .. |Build_Status| image:: https://img.shields.io/travis/neutronX/django-markdownx.svg
 .. |Format| image:: https://img.shields.io/pypi/format/django-markdownx.svg
 .. |Supported_versions_of_Python| image:: https://img.shields.io/pypi/pyversions/django-markdownx.svg
-.. |Supported_versions_of_Django| image:: https://img.shields.io/badge/Django-1.8,%201.9,%201.10,%201.11,%202.0-green.svg
+.. |Supported_versions_of_Django| image:: https://img.shields.io/badge/Django-1.8,%201.9,%201.10,%201.11,%202.0,%202.1-green.svg
 .. |License| image:: https://img.shields.io/pypi/l/django-markdownx.svg

dev.py

@@ -37,7 +37,10 @@ from sys import executable as python_path
 from sys import exit as sys_exit
 
 # Third party libraries:
-from pip import main as pip_main
+try:
+    from pip._internal import main as pip_main
+except ImportError:  # pip < 10
+    from pip import main as pip_main
 
 
 BASE_DIR = dirname(abspath(__file__))

setup.py

@@ -110,6 +110,7 @@ setup(
         'Framework :: Django :: 1.10',
         'Framework :: Django :: 1.11',
         'Framework :: Django :: 2.0',
+        'Framework :: Django :: 2.1',
         'Intended Audience :: Developers',
         'License :: OSI Approved :: BSD License',
         'Operating System :: OS Independent',