Revert "Modified plugin.json to suppress annoying deprecation warning and file not found warning."

This reverts commit 85361ec644484005d050271dbc113e70aac58ea4.
Modified plugin.json to suppress annoying deprecation warning and file not found warning.

warn: [plugins/nodebb-plugin-dailymotion] staticDir is deprecated, use staticDirs instead
warn: [meta/css] File not found! nodebb-plugin-dailymotion/style.css (reverted from commit 85361ec644484005d050271dbc113e70aac58ea4)