Latest version has Syntax Error in core.py on Python 2.6

[jeffp123]

When I import from dyn.tm.session, I get a syntax error:

Traceback (most recent call last):
  File "dyn-python-test.py", line 1, in <module>
    from dyn.tm.session import DynectSession
  File "/usr/local/lib/python2.6/site-packages/dyn/tm/session.py", line 8, in <module>
    from ..core import SessionEngine
  File "/usr/local/lib/python2.6/site-packages/dyn/core.py", line 23
    return {x: dict_obj[x] for x in dict_obj if dict_obj[x] is not None and
                             ^
SyntaxError: invalid syntax

I am using Python 2.6.5:

$ python --version
Python 2.6.5

and dyn-python-1.1.0

It looks like dict comprehension is a Python 2.7 feature:
https://www.python.org/dev/peps/pep-0274/

However, the documentation says:
"Requires Python 2.6 or higher, or the "simplejson" package."

I suspect that a simple fix would be to change that line to this:

return dict((x, dict_obj[x]) for x in dict_obj if dict_obj[x] is not None and
        not hasattr(dict_obj[x], '__call__'))

However, after doing that it looks like there are other places that are also not Python 2.6 compatible.

So, it might be best to just update the docs to let everyone know that it is not compatible with Python 2.6.

[jeffp123]

This is also a problem with previous versions. I am getting this error in all releases, going back to 1.0.1, using Python 2.6:

Traceback (most recent call last):
  File "/usr/local/lib/python2.6/site-packages/dyn/__init__.py", line 16, in <module>
    __title__      = '{} version {}'.format(__name__, __version__)

Using format strings without indexes (i.e. '{0} version {1}') was introduced in Python 2.7.

[derekargueta]

@Northover At this point in time, I think it's reasonable to move support to Python 2.7+ and update the README