Fix bug: options of aha-column could be accumulated in some rare case.

Author: liuwenchao

dist/aha-table.html

@@ -769,6 +769,7 @@
 			searchplaceholder: undefined,
 			ready: function() {
 				if (this.dataset.choices) {
+					this.options=[];
 					var choices = JSON.parse(this.dataset.choices);
 					for(option in choices) {
 						this.options.push({'value': option, 'label': choices[option]});
@@ -777,4 +778,4 @@
 			}
 		});
 	</script>
-</polymer-element>
+</polymer-element>

src/aha-table.html

@@ -769,6 +769,7 @@
 			searchplaceholder: undefined,
 			ready: function() {
 				if (this.dataset.choices) {
+					this.options=[];
 					var choices = JSON.parse(this.dataset.choices);
 					for(option in choices) {
 						this.options.push({'value': option, 'label': choices[option]});
@@ -777,4 +778,4 @@
 			}
 		});
 	</script>
-</polymer-element>
+</polymer-element>