Bump version 3.0.0 -> 3.1.0

[pacoorozco]

NOTE: The way that a Badge is triggered after a Question is answered has changed. Currently, Questions will trigger the completion of the Badge that contains matching tags.

Added

• Dispatched event UserProfileUpdated when the user's profile has been modified.
• Add password validation: min. 8 characters, including mixed cased letters, numbers and symbols.
• Forgot password capability to allow users to recover their accounts..(#284)
• Implement user's registration, in order to allow users to register themselves.
• User's notifications after user creation/registration.
• Badges can be tagged in order to filter which Questions will trigger the completion. (#309)

Changed

• Remove sensible information (like gender, url, phone...) from the user's profile. (#256)
• Fix HTTP method for the user's profile update to PUT.
• Update dependencies. (#262, #263, #264, #265, #266)
• Protect the whole application to ensure users has verified their email address.
• Protect user's profile edit through password confirmation.
• The User, Level, Badge and Question screens has been refactored to make it more user-friendly.
• Improved test coverage.

Fixed

• Error showing Badges with more than one actuator.
• Issue when uploading badge images. (#257)

Removed

• Admins can't create or modify user's password in favor of Forgot password capability. (#285)
• Question's actions has been removed in favor of the use of Tagging. (#309)