Don't throw a TypeError for requirements.txt in Python 3

Opening the file as `r` instead or `rb` ensures that we don't have
any implicit encoding/decoding of strings (so Python 3 is happy).
Includes a test that passes on both Python 2 and Python 3 which
checks this works correctly.

pipenv/cli.py

@@ -330,7 +330,7 @@ def cli(ctx, where=False, bare=False, three=False):
 @click.argument('package_name', default=False)
 @click.argument('more_packages', nargs=-1)
 @click.option('--dev','-d', is_flag=True, default=False, help="Install package(s) in [dev-packages].")
-@click.option('-r', type=click.File('rb'), default=None, help="Use requirements.txt file.")
+@click.option('-r', type=click.File('r'), default=None, help="Use requirements.txt file.")
 @click.option('--system', is_flag=True, default=False, help="System pip management.")
 def install(package_name=False, more_packages=False, r=False, dev=False, system=False):
 

test_pipenv.py

@@ -1,5 +1,6 @@
 import pytest
 
+from pipenv.cli import from_requirements_file
 import pipenv.utils
 
 
@@ -58,3 +59,19 @@ def test_convert_from_pip():
     assert dep == {u'MyProject': {u'svn': u'svn://svn.myproject.org/svn/MyProject', 'editable': True}}
 
 
+def test_install_from_requirements_file():
+
+    # requests
+    r = open('tests/requirements_requests.txt')
+    dep = from_requirements_file(r)
+    assert dep == ['requests']
+
+    # Django>1.10
+    r = open('tests/requirements_django.txt')
+    dep = from_requirements_file(r)
+    assert dep == ['Django>1.10']
+
+    # requests[sock]
+    r = open('tests/requirements_requests_socks.txt')
+    dep = from_requirements_file(r)
+    assert dep == ['requests[socks]']

tests/requirements_django.txt

@@ -0,0 +1 @@
+Django>1.10

tests/requirements_requests.txt

@@ -0,0 +1 @@
+requests

tests/requirements_requests_socks.txt

@@ -0,0 +1 @@
+requests[socks]