Gracefully handling CSRF token expiry

Gracefully handling CSRF token expiration error (#19)

- redirecting back with an error message when CSRF token has expired

Allow deleting Profile Picture

• adding Delete button for deleting Profile Picture
• Deleting old Profile Picture files upon uploading a new Profile Picture

Showing resized Profile Picture in Messages

When uploading new Profile Picture for Character 2 additional smaller sized versions of the image created: Small and Icon.
The Small sized version is used in Message conversation avatar display.

v: When uploading profile picture 3 different sized are created (#17)

- full size is used for Character Profile view
- small size used for Messages

Online/Offline indicator in Character list on Location page

Last User activity is cached with expiry of 5 minutes. The cache key is used to determine whether the User Character is Online or Offline.
Hence after 5 minutes of inactivity the User is considered to be Offline.
NPC's have nothing shown next to them, since Online/Offline indicator is irrelevant to them.

Users can upload profile picture

Users can now upload a new profile picture instead of the default one

Before introducing image upload

Refactoring: abstracting Eloquent model use + some fixes (#14)

* Moving character attacking from CharacterRuleSet into Battle

- adding `winner_xp_gained` field to Battle
- different colors for successful hit in BattleTurn's

* Adding explanation to readme.md regarding enabling Task Scheduling on Windows

* Removing redundant calculateHP method from Battle

* Moving CharacterRuleSet functionality into the Character model

* Increasing total character hit points on constitution increase

* Character model: Creating separation between Persistence and Domain by adding abstractions

* Extracting interfaces for the rest of the models

* Adding RaceRepository and using it in CharacterController::create()

* Extracting UserInterface from User + separating Persistence and Model during Character creation

* Race Model: abstracting model fields access with getters.

* Moving Character model persistence and association to User to UserRepository

* Using `push()` on Battle instead of saving multiple Character record during a fight

* Using `$this->attacks()->create()` to add new Battle record for the attacking Character

* Further refactoring of Battle::execute method

- removing updating Model Contracts methods
- adding more getters to CharacterInterface instead of Character property access

* Adding some attributes getters and applyDamage to CharacterInterface instead of Character property access

* Additional abstraction of Model attributes

* Using redirect instead of error when trying to move to non-accessible location

- converting MoveCharacterRequest to CanMoveToLocationMiddleware

* Preventing attacking in the following cases
 - knocked out characters,
 - preventing attacking when character is knocked out
 - prevent attacking yourself

* Fixing LocationInterface::addAdjacentLocation() signature