LPS - 42356 Save/Cancel buttons are cutoff when large/long logo is uploaded on Portal Settings page

Jira ticket: https://issues.liferay.com/browse/LPS-42356
Original pull request: https://github.com/herious1989/liferay-portal-ee/pull/1
Affected version: master

- Tested in Chrome, Firefox, IE 9, 10 and 11
    - Issue is not found in Chrome and all IEs

- Bug is only found in Firefox, it is not related to JIRA issue
    - In Firefox, the uploaded logo image is shown in full size which will cause it to overflow the normal site's width
    - The bug is fixed with minimal modification