Maintain dietary state when form is invalid.

Previously we only set the dietary restrictions if the RSVP was saved.
Now we set them before attempting to save the RSVP. (Rails will save the
dietary restriction changes only if the rest of the RSVP is saved.)

Fixes #256.
Merge branch 'maintain-dietary-state-when-form-is-invalid' of https://github.com/eostrom/bridge_troll into eostrom-maintain-dietary-state-when-form-is-invalid
Tweak language for email permissions checkbox
'bundle update' all the things

...except icalendar, because updating it makes tests fail
Rails 4 upgrade
* update a lot of gems
* update application.rb for rails 4
* added config.eager_load to the environment files
* updated conditions hashes on has_many relations to use lambdas
* updated schema to rails 4 format
* .scoped has become .all
* implicit table joins need .references
* get rid of whiny nils
* secret_token is now secret_key_base

Fix additional test troubles caused by Rails 4 upgrade
* Fix weird nag in SectionArranger group by statement somehow caused by rails 4
* Whitelist all accessable 'user' fields in devise 3's param sanitizer
* Omit ActiveRecord::SchemaMigration from seeds_spec leak checking
* Fix test failure caused by an as_json now returning strings instead of symbols
Clean up Guardfile