New POST /v1/user/update API endpoint

[sergeychernyshev]

Create a new endpoint for updating user's info.

POST /v1/user/update

Parameters:

• name - string (user’s name)
• email - string (sets email change attempt, but requires email confirmation to update existing address before it is shown)

Returns no object if successful

Throws exceptions:

• BadParameterException if name is empty
• BadParameterException if email is invalid
• UnauthorizedException if email is already taken

Existing form-based implementation can be found here:
https://github.com/StartupAPI/users/blob/master/edit.php#L53-L90

Move email validation into User::setEmail() and name validation into User::setName() methods instead of UI, create new validation exception classes and throw exceptions to catch in the UI and APIs. Update edit.php to also use same exceptions.