update certifi to 2015.11.20

--HG--
branch : sync_certifi

Update tox tests so they run the full suite of tests using the canonical technique. Include .tox in norecursedirs to avoid testing all the dependencies and environment. Update docs to reflect findings (https://bitbucket.org/spookylukey/setuptools/commits/88339d2e4af661a60a42bc14c4ff3e68cd19fa21#comment-2558164).

Draft a test for testing the new expectation for develop command (and general functionality when console scripts are present).

Adapt the dist to suppress the version in the requirement when installing scripts under the develop command. Fixes #439.