[Backport to 11.0] List of supported browsers is outdated and incorrect

The list of supported browsers that is checked at the login page is incorrect. In Hippo 11 we dropped support for IE10, but the login page configuration still contains "ie 10 >=". The configured versions of Firefox, Chrome and Safari are also quite outdated. Officially we state "lastest stable version", which would be Firefox 48, Chrome 52 and Safari 9. However, the configuration still defines "firefox 31 >=", "chrome 40 >=" and "safari 7 >=".

Related: the Hippo system requirements state "Mac OS X 10.8 and higher", while version 10.8 still supports Safari 6. It would make more sense to require Safari 9, and hence Mac OS X 10.9 and higher (see the list of supported Safari versions of Mac OS X).