imagediff: Update approval images for latest Mac OSX Java (font for the default JButton has changed)

openjdk version "1.7.0-u8-b04"
OpenJDK Runtime Environment (build 1.7.0-u8-b04-20120823)
OpenJDK 64-Bit Server VM (build 23.4-b01, mixed mode)
[maven-release-plugin] prepare release imagecomparison-parent-0.3.0