set minimal version in pyramid requirement (>=1.4)

as with 1.3.2 we got the following error:
 File
 "/usr/lib64/python2.7/site-packages/mobyle.web-0.0-py2.7.egg/mobyle/web/__init__.py",
 line 41, in main
     authentication_policy = AuthTktAuthenticationPolicy('seekrit',
     callback=groupFinder,hashalg='sha512')
     TypeError: __init__() got an unexpected keyword argument 'hashalg'

 when the server is start (pserve --reload development.ini)
Merge branch 'develop' of https://github.com/mobyle2/mobyle2.web into develop