always create default users

For old notebooks, there was no default user
and so certain functionality such as documentation
would not work with recent sage.
This patch makes sure that the default users are
always created if they are not present.
Remove symbolic link
Move flask_version to inside sagenb
remove flask_version from sdist MANIFEST.in
Rename ../flask_version to flask_version in RU translation
few more ../flask changes
Merge pull request #204 from ppurka/issue-203-flask

Move flask_version directory
Doctest fix for sphinx 1.2
Update settings.py

Make 'settings_page' function check password and e-mail for validity as required by the 'login' function in authentication.py
for the password.
Merge pull request #217 from kapilhp/patch-1

Update settings.py to ensure that change in user password and email address gives proper error messages.
update instructions for modifying sagenb in HACKING.rst
use sagenb-git instead of sagenb to avoid confusion
remove $ from SAGE_ROOT to improve consistency with Sage docs
Merge pull request #215 from SnarkBoojum/master

Doctest fix for sphinx 1.2
Fix a.control-select bug in div#share-publish-buttons for Worksheet and Revisions
Spanish translation completed
A lot of Typos fixed and first comments added
Upload - subir issues fixed
title in links - clave-contraseña and minor typos
Present to infinitive and minor typos