DS-2313: Mirage2 svg logo fix for ie10

This is a fix for the logo scaling issue in IE10, described in the ticket below.
The proposed solution in the ticket was to use a png fallback. We chose to fix this issue by changing the width and height of the svg file to the size used in dspace. This is a better solution than using a fallback because IE10 does not support conditional comments. This means we would have to rely on javascript to provide the fallback. 

https://jira.duraspace.org/browse/DS-2313