Convert requirements to pipenv

Fixes: pyvec#11

.travis.yml

@@ -7,10 +7,9 @@ notifications:
   email: false
 install:
 # pytest is already installed, we need a greater version
-- pip install --upgrade pytest
-- pip install -r requirements.txt
+- pipenv install --dev
 script:
-- pytest
+- pipenv run pytest
 branches:
   only:
     master

Pipfile

@@ -0,0 +1,26 @@
+[[source]]
+name = "pypi"
+url = "https://pypi.org/simple"
+verify_ssl = true
+
+[dev-packages]
+pytest = "*"
+
+[packages]
+arca = ">=0.3.1"
+pytest = "*"
+pytest-cov = "*"
+pytest-flake8 = "*"
+pytest-mock = "*"
+requests = "*"
+requests-mock = "*"
+giturlparse = "*"
+raven = {extras = ["flask"],version = "*"}
+Flask = "*"
+PyYAML = "*"
+TravisPy = "*"
+GitHub-Flask = "*"
+Flask-Session = "*"
+
+[requires]
+python_version = "3.7"