a convenient Icon behavior
Revert "a convenient Icon behavior"

This reverts commit 517399b29c928b83148d542ea8d00f042d9a9aa6.
white space not shown even with label not empty.
add factory methods for AJAX link: same as BootstrapAjaxButton
setRenderBodyOnly not needed
Javadoc fix
Merge pull request #336 from reiern70/master

some changes to buttons