DSSP test: support more versions.
Fix DSSP changes under Python 2.5 (with statement)
Turn PDB numpy import error into MissingPythonDependencyError

This is an ImportError subclass, so shouldn't break anything.
It has the benefit of making things cleaner in the unit tests,
e.g. test_DSSP_tool.py
Python 3 fix for test_DSSP_tool.py
Fix copy & paste error in last commit.
Version bump for Biopython 1.62 release
Adding a few more contributors to Biopython 1.62
Post release version bump
Update .travis.yml to drop Python 2.5
Remove with_statement imports required under Python 2.5

Removed all the with statement imports
(and any comment lines associated with them);

from __future__ import with_statement
Update setup.py now we've dropped Python 2.5
Start recording contributors to the next release
Use byte literals (new in Python 2.6).

The old constants were defined via our _as_bytes function
in order to work under Python 2.5 as well.
Update DEPRECATED file entry for Python 2.5

Documentation change only, skip TravisCI testing [ci skip]