ISIS-987 Provide some sort of mechanism to allow users to self-register for an Isis application.

Add SignUp page and mail sending service
ISIS-987 Provide some sort of mechanism to allow users to self-register for an Isis application.

Add register (email), verify, register user data flow.
ISIS-987 Provide some sort of mechanism to allow users to self-register for an Isis application.

UI improvements for Sign Up and Registration panels
ISIS-987 Provide some sort of mechanism to allow users to self-register for an Isis application.

Extract an abstract page for all account management related pages - AccountManagementPageAbstract.
ISIS-987 Provide some sort of mechanism to allow users to self-register for an Isis application.

Add validator that checks whether there is a user with a given email.
Add TODO to PasswordReset logic.