User management

(fufills #72 and #32, per @redsquirrel)

* Edit original "activation" email as the content might be misleading
* Send management link email after activation
* Allow user to request a resend of their activation email like so:

Current WIP:

User goes to home page, clicks "Manage my appointments"

![screenshot 2014-03-04 14 50 53](https://f.cloud.github.com/assets/202/2326989/fb759fb8-a3e9-11e3-8f53-0427575c906d.png)

They are taken to a page to enter their email address to retrieve user management link:

![screenshot 2014-03-04 14 51 06](https://f.cloud.github.com/assets/202/2326993/03943af6-a3ea-11e3-88ca-4f4980790e45.png)

If the user enters an email address not belonging to a user, an notice is shown:

![screenshot 2014-03-04 14 51 22](https://f.cloud.github.com/assets/202/2326994/0a56c200-a3ea-11e3-9008-641485d66e07.png)

If the user is found, a success notice is shown

![screenshot 2014-03-04 14 51 40](https://f.cloud.github.com/assets/202/2326996/10553808-a3ea-11e3-9d0c-bb2fa45c9979.png)

And an email is sent to said user:

![screenshot 2014-03-04 14 57 12](https://f.cloud.github.com/assets/202/2326997/164f2fc0-a3ea-11e3-95e0-bd8c0f2762bd.png)