Branding changes (#24) ...

- Removed the description field from organisation
- Added a contact email field to organization
- Added an email address validator
- Updated organisation logo upload so that the system will resize the image to the correct height rather than forcing the user to provide a 100x100 image
- Change how the organisation logo is displayed 

* updated organisation edit page's error messages so that errors are placed in the alert text section. Updated wording in locale files to reflect the 160x160 file size.

* removed height and width constraints to logo upload function. Added method that will resize the uploaded logo so that the width is 160px (maintaining aspect ratio) so that the logo fits within the layout properly

* changed logo size to a height of 100 and moved logo so that it appears alongside the DMPRoadmap logo per the current specifications

* Removed description field from organisation. Add contact email to the organisation. Change the way the logo is displayed on the organisation screen.