añadido tema de stanford
Merge branch 'master' of https://github.com/edx/edx-platform
Merge branch 'master' of https://github.com/edx/edx-platform
Merge branch 'master' of git.iaen.edu.ec:edx-platform
[IMP] agrega configuracion i18n para es latino, codigo de lenguaje es_419 segun la wiki de edx-plataform
[IMP] agregado archivo de configuracion para lenguaje es_149
[FIX] configurado para es_419
[IMP] archivos PO generados desde transifex y sync, la traduccion en transifex esta al 100%
[IMP] aplicada configuracion de desarrollo para mysql
[IMP] agregada configuracion de staging
LMS: add CSRF token to register form
Add Neurolit to AUTHORS file
Set empty aws credentials to None.
Changed create_enrollment to create_or_update_enrollment
all CourseEnrollment modifications route through create_or_update
purchased_callback now uses the change_mode method
Studio: resolves IE notifications display issue and abstracts CSS to avoid IE selector/rule limit
STUD-815
more granular transactions in grading [LMS-1480]

remove field_data_cache from grades.grade and grades.progress_summary

cleans grading code by adding wrappers
Merge pull request #1655 from edx/adam/more-granular-grading-transactions

Adam/more granular grading transactions
Persist student answers on input error

LMS-469