Split requirements.txt into multiple files.

README.dev.md

@@ -1094,7 +1094,7 @@ Make sure you have followed the steps specific for your platform:
 And then do the following steps that are common to all platforms:
 
 ```
-pip install --no-deps -r requirements.txt
+pip install --no-deps -r requirements/dev.txt
 ./tools/setup/install-phantomjs
 ./tools/install-mypy
 ./tools/setup/download-zxcvbn

prod.txt

@@ -0,0 +1 @@
+-r common.txt

provision.py

@@ -200,7 +200,7 @@ def main():
     setup_virtualenv(PY3_VENV_PATH,
                      os.path.join(ZULIP_PATH, "requirements", "mypy.txt"),
                      virtualenv_args=['-p', 'python3'])
-    setup_virtualenv(VENV_PATH, os.path.join(ZULIP_PATH, "requirements.txt"))
+    setup_virtualenv(VENV_PATH, os.path.join(ZULIP_PATH, "requirements", "dev.txt"))
 
     # Put Python2 virtualenv activation in our .bash_profile.
     with open(os.path.expanduser('~/.bash_profile'), 'w+') as bash_profile:

requirements/common.txt

@@ -30,7 +30,6 @@ docutils==0.12 # Dependency of Sphinx
 docopt==0.4.0
 enum34==1.0.4
 fonttools==3.0
-future==0.15.2
 gcm-client==0.1.4
 gitdb==0.6.4
 google-api-python-client==1.4.0
@@ -46,7 +45,6 @@ itsdangerous==0.24  # Dependency of moto s3 mock
 jwt==0.3.2
 mandrill==1.0.57
 mock==1.0.1
-modernize==0.5
 moto==0.4.23  # Dependency of moto s3 mock
 oauth2client==1.4.11
 oauthlib==1.0.3

requirements/dev.txt

@@ -0,0 +1,2 @@
+-r common.txt
+-r py3k.txt