password updates - Show/hide passwords & 8 character min help text.

* Add a styled checkbox to each password field that toggles the show and hide.
* To show a password, change the input field type to "text"
* Add unit tests for the affected views
* Add "Must be at least 8 characters" to each screen below the password field.

fixes #253
fixes #264

It looks like:

![screen shot 2014-01-17 at 16 07 41](https://f.cloud.github.com/assets/848085/1941928/a15f28a4-7f91-11e3-9ee5-12f869b37347.png)

and 


![screen shot 2014-01-17 at 16 07 47](https://f.cloud.github.com/assets/848085/1941929/a2e287d4-7f91-11e3-9ad4-d4e56cff5560.png)