move PivotTableRenderModel in base package and PivotCsvExporter in exporter package
add demo/db in gitignore
Refactored the exporters into plugins; Currently only the CSV plugin exists, and is selected by default.
Refactored the exporters into plugins; Currently only the CSV plugin exists, and is selected by default.
Basic version of a XLS exporter using POI
Added some basic styling to the excel exporter
Merge remote-tracking branch 'upstream/master' into exporter_plugins

Conflicts:
	wicket-pivot/src/main/java/ro/fortsoft/wicket/pivot/PivotTableRenderModel.java
	wicket-pivot/src/main/java/ro/fortsoft/wicket/pivot/exporter/PivotCsvExporter.java
	wicket-pivot/src/main/java/ro/fortsoft/wicket/pivot/web/PivotPanel.java
Merge remote-tracking branch 'upstream/master'

Conflicts:
	wicket-pivot/src/main/java/ro/fortsoft/wicket/pivot/PivotTableRenderModel.java
	wicket-pivot/src/main/java/ro/fortsoft/wicket/pivot/exporter/PivotCsvExporter.java
	wicket-pivot/src/main/java/ro/fortsoft/wicket/pivot/web/PivotPanel.java
Merge branch 'exporter_plugins'

Conflicts:
	wicket-pivot/src/main/java/ro/fortsoft/wicket/pivot/exporter/PivotCsvExporter.java
Internal Version bump