Python 3 compatibility

Hello,

The executable can not be used when the default python interpreter is python3.2:

$ disper --version
  File "/usr/bin/disper", line 34
    except Exception,e:
                    ^
SyntaxError: invalid syntax

Suggested solution: update dependency metadata to require python2.7 (or some other python 2.x metapackage), and patch the executable script from:
#!/usr/bin/env python
to:
#!/usr/bin/python2.7
(or /usr/bin/python2)

Long term solution: contact upstream developer and add support for all supported Python versions.

Thanks,
Amir