added "show values" to bar chart

Conflicts:
	EazeGraphLibrary/src/main/java/org/eazegraph/lib/charts/BarChart.java
	EazeGraphLibrary/src/main/java/org/eazegraph/lib/charts/BaseChart.java
resolved conflict
canvas renamed to _Canvas
Merge pull request #14 from j4velin/showValues

Added mShowValues attribute which determines if the value of each data should be drawn in the graph