- change a few comments / strings
- move extract_choices into the ChoiceGroup class

- small Attribute and InputTypeBase interface changes to make things cleaner
- move html quoting into templates (use ${blah | h} syntax)
- converting input types to use new format.

- add an Attribute class
- input types just need to declare which attributes they want, and how to transform and validate them, and the base class will do all the rest.
- change OptionInput to new format.

Feature/victor/inputtypes refactor

Add HD control to video player

Add google analytics to course info pages

Update Job Page with new positions

Allow optional advertised_start metadata in Course

Add MySQL-python to the requirements.

Allow optional advertised_start metadata in Course, to let people pre-launch thier courses quietly if desired.

Feature/victor/inputtypes refactor
- addressed comments and added a few TODOs.  Merging.

- all inputtypes should have id inputtype_${id}
- should have class capa_inputtype

- allows catching any exceptions and making sure the xml is in the error message
- isolates subclasses from external interface a bit

Remove non-working TrueFalse functionality from choicegroup, combine tests with radiogroup and checkboxgroup

Feature/arjun/allow save

Update startup script for 12.10 Ubuntu.

Added "quantal" to the list of known distribution names.

Improve fileinput message

Support for multiple rectangle hitboxes in imageresponse