Preparing release 3.1.6

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.1-stable@2723 ed100bfc-0583-0410-97f2-c26b58777a21
Back to development: 3.1.7

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.1-stable@2724 ed100bfc-0583-0410-97f2-c26b58777a21
Travis no longer requires any goofy has for Numpy on Python 3 to work.  Also add builds for 3.3 and 3.4

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.1-stable@2727 ed100bfc-0583-0410-97f2-c26b58777a21