Allow access from remote hosts

[kevin-bates]

As of Notebook PR 3714 access from non-local hosts is being denied by default. Since this is the primary functionality provided by Kernel Gateway, we should always enable the ability to provide access from remote hosts. (The same change was required in Enterprise Gateway.)

[rolweber]

The PR also removed Python 3.3 from the Travis CI configuration. I don't remember whether removing support for Python 3.3 was already discussed, but I'm all for it :-)

[kevin-bates]

Shoot - I'm sorry, I meant to include something like the following...

I've removed 3.3 from the Travis config since pkg_resources (via setuptools) no longer supports Python 3.3. That update was merged late May and delivered in release 40.0.0 July 8th.

$ python --version
Python 3.3.6
$ pip --version
pip 8.1.2 from /home/travis/virtualenv/python3.3.6/lib/python3.3/site-packages (python 3.3)
install.1
4.07s$ pip install --upgrade setuptools pip
Collecting setuptools
  Downloading https://files.pythonhosted.org/packages/ff/f4/385715ccc461885f3cedf57a41ae3c12b5fec3f35cce4c8706b1a112a133/setuptools-40.0.0-py2.py3-none-any.whl (567kB)
    100% |████████████████████████████████| 573kB 452kB/s 
Collecting pip
  Downloading https://files.pythonhosted.org/packages/0f/74/ecd13431bcc456ed390b44c8a6e917c1820365cbebcb6a8974d1cd045ab4/pip-10.0.1-py2.py3-none-any.whl (1.3MB)
    100% |████████████████████████████████| 1.3MB 1.1MB/s 
Installing collected packages: setuptools, pip
  Found existing installation: setuptools 18.0.1
    Uninstalling setuptools-18.0.1:
      Successfully uninstalled setuptools-18.0.1
  Found existing installation: pip 8.1.2
    Uninstalling pip-8.1.2:
      Successfully uninstalled pip-8.1.2
Successfully installed pip-7.1.2 setuptools-40.0.0
0.18s$ python setup.py bdist_wheel sdist
Traceback (most recent call last):
  File "setup.py", line 6, in <module>
    from setuptools import setup
  File "/home/travis/virtualenv/python3.3.6/lib/python3.3/site-packages/setuptools/__init__.py", line 12, in <module>
    import setuptools.version
  File "/home/travis/virtualenv/python3.3.6/lib/python3.3/site-packages/setuptools/version.py", line 1, in <module>
    import pkg_resources
  File "/home/travis/virtualenv/python3.3.6/lib/python3.3/site-packages/pkg_resources/__init__.py", line 85, in <module>
    raise RuntimeError("Python 3.4 or later is required")
RuntimeError: Python 3.4 or later is required