now using examples/em_test.pickle as editorial model for new instances

+ a new validator named 'string', it tries to cast the conf value using str()

- separates LeGetQuery tests and LeFilteredQuery tests
- small bugfixes associated to tests

- adds tests on filter parse & check
 - standart filters parse & check
 - relational filters parse & check
- bugfixes related to tests in query.py
- update the example and the test EM
- bugfixes in admin script

Doing so forbids operators like << == =! in* etc..
The tests were updated

- the re for filter spliting is modified to better handle operators
- added leading & trailing space to some operators

To start in standalone uwsgi set lodel2.webui.standalone=True in conf file and start loader.py

- load variables from settings
- import loader.py

- create_instance.sh create some symbolic links
- webui plugin that add webui configuration variable

- fixes exceptions output
- add "none" validator that validates only None