basic flexisettings settings proxy

this can be called through DJANGO_SETTINGS_MODULE without breaking django
import wrapped settings

* import settings through the proxy
* create a dictionary to cache import results
* add attribute access through __getattribute__()
* rename proxy class to FlexiSettingsProxy
add pip requirements file
basic unit testing
rename tests.base to tests.imports
add more imports tests

added test suite to make sure tests run in a certain order. Playing with
imports without unloading is messy and unloading modules is always a complex
task.
add comments about namespace pollution in tests
move common setUp() and tearDown() to base class
move from unittest to unittest2

this will provide things like setUpClass and tearDownClass
add setUpClass and tearDownClass in tests.base
create tests for settings lookup
add basic import mechanisms

add fake import and import env, security, settings files
fix bug in settings precedence in _globals dict

variables could not be overwritten by later reference in another file
add a list of wrapped settings modules

accessible through _wrapped_modules list
add special flexi settings files to tests
add settings import to tests __init__
test for local settings import
test for FLEXI_RUN_ENV
fix a bug when settings name starts with '_'
more methods descriptions