Refactor setup.py to work with pip 10 (#34)

* Refactor setup.py to work with pip 10
Warning: Not backwards compatible with older pip versions !

* Bump version number

.travis.yml

@@ -13,6 +13,7 @@ matrix:
     - env: DJANGO='>=2.0,<2.1'
       python: "2.7.13"
 install:
+   - pip install --upgrade pip
    - pip install -e .
    - pip install -r requirements/requirements_test.txt
    - pip install "Django${DJANGO}"

setup.py

@@ -1,6 +1,6 @@
 from setuptools import setup, find_packages
-from pip.req import parse_requirements
-from pip.download import PipSession
+from pip._internal.req.req_file import parse_requirements
+from pip._internal.download import PipSession
 
 from os import path
 from smsgateway import __version__

smsgateway/__init__.py

@@ -1,5 +1,5 @@
 from __future__ import absolute_import
-__version__ = '2.1.13'
+__version__ = '2.1.14'
 
 
 def get_account(using=None):