Allow to define 'hide_individual_votes' on instance level

This is as experimental as the global setting.
Merge pull request #897 from nidico/feature-hide-individual-votes-per-instance

Allow to define 'hide_individual_votes' on instance level
add hologram styleguide generator
create some example CSS docs
style styleguide page navigation
Merge pull request #898 from xi/feature-hologram

hologram styleguide
Don't try to solr index form-feed characters

This makes sure we don't try to solr index form-feed characters. The
same has been done for vertical-tab characters in
c588a8bd6d96252325eadd6ee87e1dcc073087fc.
Don't allow amendment creation for non-joined members
Fix userbadge assignment within overlay
remove unneeded import
Also require page.edit_head for container page edit
Proper permission check for container page edit in template

This is now consistent with the permission checks on the actual edit
controller and with show_sectionpage.
Optionally require user to check terms on register
Merge pull request #900 from nidico/feature-fix-userbadge-assignment

Fix userbadge assignment within overlay
accept_terms: improved error message
allow to link to inline rows

the link is available from the expand button
fix page.edit_head error msg
Merge pull request #901 from nidico/feature-fix-container-page-edit

Fix containerpage edit permissions
fix agree terms wording
fix guard state

the guard decorator was not thread-safe. This allowed perpetrators to
let other users execute controller functions with manipulated
parameters. However, I could not find any critical exploits based on
this bug.