Change some button colors

Changed button classes to btn-primary (blue) or btn-success (green)
in a few places:

* Login page: blue "Log in" button
* Save password change: green
* Save changes button when editing box: green
* Submit button on financial aid and proposal review pages: green
Merge pull request #110 from caktus/feature/110-button-styling

[Settings] Normalize Settings vs Change Password Save button