Changed "x-" to "x." for new MIME types according to RFC6838.

http://www.rfc-editor.org/rfc/rfc6838.txt
Centered forms. Large buttons. Error report when unable to start fwk.

 * Added support for centered forms
 * Added support for extra large buttons
 * Centered most of the FirstUse forms.
 * A download link is provided with error messages and stacktrace when the Web UI is unable to start the Pipeline 2 engine.
 * When an error message starts with «'java'», a message is displayed describing how to add Java to the PATH variable in Windows.
 * Also started work on a short "how to install java" guide for when the Web UI fails to start.