update gems to work with rails4
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
strong parameters: account update for devise
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.
Merge pull request #432 from doitian/rails4-event-has-should-return-boolean

[Rails4] Force Event#has? to return boolean
Merge pull request #429 from doitian/rails4-fix-datatime-to-s

[Rails4] Fix `datetime.to_s(:db)`
Merge pull request #428 from doitian/rails4-fix-obsolete-rspec-stub-syntax

[Rails4] Fix obsoleted rspec stub syntax.
add to_ng_init method to Hash class.
Merge pull request #430 from ichord/rails4

[Rails4] update config