helpers: remove direct global imports from model To avoid circular imports, we need to determine some 'rules'. Helpers have minimal dependencies to model. Most of the model imports that are currently global are only used in a few methods. Therefore, it makes sense to make these imports local to the method, so they won't 'count' for circular imports at module level.

[tox]
minversion = 1.8
envlist = py{26,27}-pytest

[testenv]
setenv =
    PYTHONHASHSEED = 0
deps =
    -r{toxinidir}/dev_requirements.txt
    py26-pytest: unittest2
    python-ldap
    python-pam
commands =
    pytest: py.test {posargs}