update headers

etc/header.txt

pom.xml

...t-demo/src/main/java/com/xeiam/xchart/demo/ChartInfo.java

...-demo/src/main/java/com/xeiam/xchart/demo/XChartDemo.java

.../main/java/com/xeiam/xchart/demo/charts/ExampleChart.java

...n/java/com/xeiam/xchart/demo/charts/area/AreaChart01.java

...n/java/com/xeiam/xchart/demo/charts/area/AreaChart02.java

...va/com/xeiam/xchart/demo/charts/area/AreaLineChart03.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart01.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart02.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart03.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart04.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart05.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart06.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart07.java

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart08.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart01.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart02.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart03.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart04.java