Anonymous edit feature (#9)

* Remove deprecated middleware
* Add password to Paste entity
* Add new custom rule to determine password match
* Improve paste menu
* Add new FormRequest for update paste
* Add fixed Paste test on PasteTableSeeder
* Add the ability to edit a paste
* Improve tests suite
* Remove dead code
* Add new alert style for callouts
* Add the ability to set a password on paste creation and fork
* Fix a bug that caused crashes when a password was null
* Fix a stupid bug on LanguageFactory causing tests to fail

Improve procedural seeds