setup.py requires specific versions of dependencies

Installing mashape-analytics alongside other packages can be problematic if those other packages have some common dependencies but with different version requirements.

Instead of requiring specific versions like this:

` install_requires=[
'pytz==2016.4',
'requests==2.9.1',
'six==1.10.0',
'ujson==1.35',
'Werkzeug==0.11.9',
],`

...can dependencies by specified as minimum versions wherever possible?

Start in setup.py and inspect the install_requires entries listed in the issue. Check which exact dependency versions can be changed to minimum versions without losing the package's stated compatibility. Done means the overly restrictive requirements are relaxed where possible and the package can still be installed with its dependencies.

索引モデルが issue の本文から書いたものです。