update gems to work with rails4
add replies count with topic in event show view
uesd border-radius mixin with scss
config: to rails4
fix strong parameters problems
change acts_as_follower gem
fix strong parameters for devise and devise_invitable
fix query statement
remove `protected attributes` usage from event spec
extend badge class in replies-count class
remove about before_save code because this has fixed in #421
strong parameters: account update for devise
Merge remote-tracking branch 'ywjno/issue_413'

Conflicts:
	app/models/group_topic_reply.rb
fix slim 2.0 deprecated warnings shown in rspec
Merge remote-tracking branch 'ichord/rails4' into rails4

Do not delete existing migration.

Conflicts:
	db/schema.rb
Fix obsoleted rspec stub syntax.

The following syntax is invalid now:

    x.stub method, return_value

It should be change to

    x.stub method => return_value

or

    x.stub(method).and_return(return_value)
Fix `datetime.to_s(:db)`

`to_s` on `nil` requires zero parameters. Use `try` to bypass calling
`to_s` on `nil`
config: add uglifier as js_compressor in `production.rb`
config: remove some unnecessary config
Force Event#has? to return boolean

Because translations `t('views.join.state'), t('views.join.title')` use
`true` and `false` as the key.