don't test with python 2.5 on travisci

looks like a pip/virtualenv bootstrapping problem:

,----
| Downloading/unpacking pytest>=2.3
|
| Exception:
|
| Traceback (most recent call last):
|
| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/basecommand.py", line 139, in main
|
| status = self.run(options, args)
|
| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/commands/install.py", line 266, in run
|
| requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
|
| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/req.py", line 1026, in prepare_files
|
| url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
|
| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/index.py", line 125, in find_requirement
|
| page = self._get_page(main_index_url, req)
|
| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/index.py", line 353, in _get_page
|
| return HTMLPage.get_page(link, req, cache=self.cache)
|
| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/index.py", line 471, in get_page
|
| resp = urlopen(url)
|
| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/download.py", line 143, in __call__
|
| response = self.get_opener(scheme=scheme).open(url)
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| File "/home/travis/build/schmir/pypiserver/.tox/py25/lib/python2.5/site-packages/pip-1.3.1-py2.5.egg/pip/download.py", line 201, in get_opener
|
| raise NoSSLError()
|
| NoSSLError:
|
| ###################################################################
|
| ## You don't have an importable ssl module. You are most ##
|
| ## likely using Python 2.5, which did not include ssl ##
|
| ## support by default. In this state, we can not provide ##
|
| ## ssl certified downloads from PyPI. ##
|
| ## ##
|
| ## You can do one of 2 things: ##
|
| ## 1) Install this: https://pypi.python.org/pypi/ssl/ ##
|
| ## (It provides ssl support for older Pythons ) ##
|
| ## 2) Use the --insecure option to allow this insecurity ##
|
| ## ##
|
| ## For more details, go to the "SSL Certificate Verification" ##
|
| ## section located here: ##
|
| ## http://www.pip-installer.org/en/latest/logic.html ##
|
| ## ##
|
| ###################################################################
|
`----