Fix errors when running migrations against MySQL 5.1.72

Fixes the following type of error:
Error in migration: askbot:0055_auto__chg_field_question_thread
ValueError: The database backend does not accept 0 as a value for AutoField.
Allow Django 1.5.x, not just 1.5 itself

setup.py says that "Django 1.3.1 - 1.5.1" are supported but REQUIREMENTS in __init__.py only allows up to 1.5.
Add CSRF protection to comment_to_answer view
Check that user can convert comments or answers
Require loggedin user on answer/comment convert
Add CSRF token in comments loaded via Javascript
modified the generate_post_snippets to re-parse full html of posts as well
added invalidation of cached data in generate_post_snippets command
Merge branch 'master' of https://github.com/ASKBOT/askbot-devel
Merge pull request #208 from brightinteractive/allow_django_15x

Allow Django 1.5.x, not just 1.5 itself
updated requirements files
Merge pull request #207 from brightinteractive/migrate_mysql_fix

Fix errors when running migrations against MySQL 5.1.72
Merge branch 'master' of https://github.com/ASKBOT/askbot-devel
some changes in the "add test content" command and in the console util library
Merge branch 'master' of github.com:ASKBOT/askbot-devel
updated the contributors list
a minor change
first pass on mozilla persona protocol
Merge branch 'master' of https://github.com/ASKBOT/askbot-devel
added email prefill with mozilla persona and error reporting for incorrect APP_URL setting