fix bar chart in demo that date starts at 0. It should be 1 or the fi…

…rst value will be 0.0

this address the first issue in ChartsOrg#1639

ChartsDemo/Classes/Demos/BarChartViewController.m

@@ -128,7 +128,7 @@ - (void)updateChartData
 
 - (void)setDataCount:(int)count range:(double)range
 {
-    double start = 0.0;
+    double start = 1.0;
 
     NSMutableArray *yVals = [[NSMutableArray alloc] init];