Massively upgrade symposion

* Remove markitup (to be replaced with Ace editor)
* Use DUA decorators
* Removed custom signup bits
* Upgraded dependencies
* Added migrations
* Namespaced template locations
* Removed html5parser/sanitizer (for now) - parsing functionality
should be moved out entirely to a hooks
* Replaced ProposalScoreExpression object with a function that returns
F() expressions

i18n all part

- forms for labels and helps
- views for success or warning messages
- apps and models verbose_names for admin

Signed-off-by: Hiroshi Miura <miurahr@linux.com>

python3 compatibility

- Things are suggested in python3 porting guide.
https://docs.djangoproject.com/en/1.8/topics/python3/

1. adding ```from django.utils.encoding import
python_2_unicode_compatible```

2. ``` __str__``` instead of ```__unicode__```
https://docs.djangoproject.com/en/1.8/topics/python3/#str-and-unicode-methods

3. Adding ```from __future__ import unicode_literals``` at the top
of your Python modules
https://docs.djangoproject.com/en/1.8/topics/python3/#unicode-literals

4. Removing the `u` prefix before unicode strings;
https://docs.djangoproject.com/en/1.8/topics/python3/#unicode-literals

- also closed #66

Signed-off-by: Hiroshi Miura <miurahr@linux.com>

multiple recipients for email

Signed-off-by: Hiroshi Miura <miurahr@linux.com>

Adds a manage.py script to assign reviewers to talks.

Requires that a 'reviewers' group exist, and that there are people assigned to it (otherwise it won't find any reviewers to add!).

It will assign up to 3 reviewers, where those reviewers are NOT one of the speakers, and that reviewer has not opted out of reviewing that talk. It will choose random reviewers from those with the fewest existing not-opted-out assignments.

Fixed bug in review deletion

When a review was not the latest it would cause a bug on deletion of the
latest. We changed the logic to work with the latest vote versus the previous
to fix this issue. Now all review deletion ensure a consistent latest vote
state.

Removed default values of one from ProposalResult denormalized fields

The original default value of one assumed ProposalResult was being created
when a Review was created which meant a comment and a vote was made. This is
no longer the case from changes after the original change and has caused off
by one errors in the denormalized count.