Site health improvements

[markkap]

List of things that need to be done

• remove/improve php check. It is hard to say what is an acceptable PHP version since some linux distributions are very slow in updating it. The only valid error indication that can be given here is that the PHP version is less then the minimal one, but if it is so, the code is not likely to work at all...
• Check connectivity to calmpress.org
• User count is worthless info.
• Media handling should probably focus on the ability to add new images, not about techno blabla that says very little even to me.
• .htaccess rules needs to be worded differently to be more explicit that there are (no) rules added "by hand" to the file. It will be nice to test if the file is even being used.
• "WordPress constants" some of those being displayed do nothing in calmPress
• "Filesystem Permission" the current wording makes it sound like those directories need to be writable while some of them should not. Either need some different wording or show just what needs to be writable.

For the status tab need to make sure all tests make sence, and probably remove their "categoring". Tests should be either mandatory, highly recommended, or optional. Need to remove the test, or invert the logic, of the auto update test.