Display Tomcat and database versions

[ChiuchiuSorin]

As part of #3 a Backend section was added to the Admin tools homepage. This section displays, among other things, information about the used server and database, as seen in the below screenshot:

It would be nice to also have the versions displayed

[ChiuchiuSorin]

• Added Active installs 2 as a dependency to access details about server version;
• Changed XWiki project version from 13.10-3 to 14.10 to use Active Installs 2;
• Added server version and database version to the displayed info;