Merge pull request #179 from vrozkovec/master

ControlGroup - set label internally to FormComponent label
use onComponentTag instead of AttributeModifier (fixes #177)
add public componentId() to Navbar (fixes #181, fixes #180)
minor improvements to *ResourceVersionTest
use onComponentTag instead of AttributeModifier (fixes #177)
add public componentId() to Navbar (fixes #181, fixes #180)
minor improvements to *ResourceVersionTest
close stream after calculating resource version
remove non-printable characters from checksum
remove non-printable characters from checksum
shutdown test application in wicket base test
minor improvements to ControlGroup, mark ControlGroupBorder as deprecated
map FATAL to "error" css class name
merge controlgroup