Require travel plans on financial aid form

More specifically, require travel plans on the financial aid
form if and only if a travel grant is requested. Implemented
by leaving the form field technically not required, adding
form validation that looks at whether a travel grant is requested,
and marking the travel plans field with 'required' styling
manually.
More translation updates

* Django settings to tell Django what languages we're using and where
  to find our translation files.
* Mark more strings for translation.
* Update the comments at the top of locale/fr/LC_MESSAGES/django.po
* Add some doc for how to translate
* Fix use of blocktrans in some templates
* Update finaid doc while I'm here
* Ran make_messages & compile_messages to update the translation files.
Limit speaker bio field to 100 words
No markdown for speaker bio; expand help text
Merge pull request #172 from caktus/feature/translation-process-2

More translation updates
Merge pull request #171 from caktus/feature/171-limit-speaker-bios

Limit speaker bios to 100 words
Merge pull request #170 from caktus/feature/travel-plans-field

Require travel plans on financial aid form
Merge branch 'develop' into feature/78-refactor-settings