fixed small rss bug

git-svn-id: https://plugins.svn.wordpress.org/network-summary/trunk@856637 b8457f37-d9ea-0310-8a92-e5e31aec5664
started on option for rss-feed limit

git-svn-id: https://plugins.svn.wordpress.org/network-summary/trunk@857289 b8457f37-d9ea-0310-8a92-e5e31aec5664
* Updated the rss feed. It is no valid rss feed. The language is always en-US and the author is the page of the post.
* RSS feed accepts category arguments, e.g. `/feed/rss2-network?category=1` will display all items of this category.
* The RSS feed now has a default limit of 50 items. The value can be changed in the network settings.
* Refactoring of the settings and options.

git-svn-id: https://plugins.svn.wordpress.org/network-summary/trunk@857547 b8457f37-d9ea-0310-8a92-e5e31aec5664
= 2.0.4 =
* Simplified RSS feed urls.
* Rewrite rules are now flushed with activation.
* Scripts to create databases now check for the correct mysql storage engine.

git-svn-id: https://plugins.svn.wordpress.org/network-summary/trunk@860298 b8457f37-d9ea-0310-8a92-e5e31aec5664