update export
Merge pull request #36 from juancjara/master

update dev
Merge branch 'development' of https://github.com/juancjara/Grades-project into development
max letters validation
votes on share courses
update login css
add relation between course shared and user
event on select
Merge pull request #38 from juancjara/master

update dev
bugs fixed
Merge pull request #40 from juancjara/master

update dev
bugs de chota
Merge pull request #41 from juancjara/development

bugs de chota