Version 0.7.1

• v0.7.1
• Add Read The Docs documentation
• Add const module identifiers back into package namespace
• Remove b prefixes from strings inserted into error messages.
• v0.7.0
• String attribute issues with Python 3 have all been resolved, and now each
  function that takes a string can handle unicode strings, and returns
  unicode strings.
• All code has been updated to use future imports for unicode_literals
  and print_function, so we're effectively writing Python 3 code now.
• PEP8 compliance changes all over the place, except those that would break
  names required by underlying C DRMAA library.
• Now automatically run unit tests of Travis-CI with SGE, and all tests pass
  for Python 2.6, 2.7, and 3.3. SGE is installed using scripts I describe
  in this gist.
• Unit tests are now in a top-level directory instead of a sub-directory
  under the drmaa package.
• There is now a session.py module that contains most of the code that was
  in __init__.py before, and __init__ just imports things and sets
  __all__ and __version__, as is typically recommended now.
• Drops support for Python 2.5.