Increase default upload space for sites on a network from 10M to 100M. props...

Increase default upload space for sites on a network from 10M to 100M. props andrea_r. fixes #18831.



git-svn-id: https://core.svn.wordpress.org/trunk@20170 1a063a9b-81f0-0310-95a4-ce76da25c4cd