Use more REST-like endpoints to change and reset password

[rodrigods]

Current change password endpoint: POST /account/pw/change
Current reset password endpoint: POST /account/pw/reset

Since we have already a endpoint to create and delete accounts:
POST /account
DELETE /account

We should use the following endpoint to change password:
PUT /account
{
"username": "alice@shakespeare.lit",
"old_password": "pass123",
"new_password": "pass456",
"email": "alice@email.com"
}

For the future, if we want endpoints to change other fields like email, or even username, we can use:

PUT /account?change=:field

And the field to be changed passed in the change parameter.

And the following to reset password:
PUT /account?reset=true
{
"username": "alice@shakespeare.lit"
}