sanitize rating comments
Merge pull request #323 from migeruhito/rating_comments

Provisional workaround to sanitize rating comments
Move babel import inside function
Update Sagenb version to 0.11.2
Update instructions to use GNU tar

This should at least partially fix Sage Trac 17490.
Correct localization information

This is not a full answer to #313 but is a start to making this information correct.
Update release instructions

Adding any relevant stuff from old release instructions,
mainly to remind of prerequisites.
Remove outdated instructions

(From the readme)
Jinja2 initialization changed and autoescape activated
'safe' added and 'escape' removed from templates
quotes left to jinja automatic autoescape