Experiment with quick sdist-and-test checks in Travis

Can't wait to move to Circle so I can do this testing locally

.travis.yml

@@ -72,6 +72,10 @@ script:
   - inv coverage
   # Ensure documentation builds, both sites, maxxed nitpicking
   - inv sites
+  # Sanity check ability to build sdist
+  - python setup.py sdist
+  # And ability to run tests from within the result
+  - cd dist && tar xzvf *.tar.gz && rm *.tar.gz && cd paramiko-* && ls -l && pip install -e . && inv test
 notifications:
   irc:
     channels: "irc.freenode.org#paramiko"

sites/www/changelog.rst

@@ -2,6 +2,8 @@
 Changelog
 =========
 
+- :support:`-` Update our CI to catch issues with sdist generation,
+  installation and testing.
 - :support:`1727` Add missing test suite fixtures directory to MANIFEST.in,
   reinstating the ability to run Paramiko's tests from an sdist tarball. Thanks
   to Sandro Tosi for reporting the issue and to Blazej Michalik for the PR.