Add password change URLs, templates, and link

[brylie]

Co-authored by: Kelvin Munyao

Closes https://github.com/GeriLife/companionship-care/issues/54

Changes:

• Allow users to change their password.

[brylie]

@all-contributors please add @Marsh-sudo for code

[allcontributors[bot]]

@brylie

I've put up a pull request to add @Marsh-sudo! :tada: