Fix for exception in chart export with Chrome

With Chrome if dimension value has character with code 160 (nbsp) chart export to image fails with exception.
The reason for this is character escaped by Chrome with &nbsp; entity in embeded svg.

org.apache.batik.transcoder.TranscoderException: null
Enclosed Exception:
The entity "nbsp" was referenced, but not declared.
	at org.apache.batik.transcoder.XMLAbstractTranscoder.transcode(XMLAbstractTranscoder.java:136)
	at org.apache.batik.transcoder.SVGAbstractTranscoder.transcode(SVGAbstractTranscoder.java:156)
	at org.saiku.web.svg.BatikConverter.convert(Converter.java:86)
	at org.saiku.web.rest.resources.ExporterResource.exportChart(ExporterResource.java:166)
	at org.saiku.web.rest.resources.ExporterResource$$FastClassByCGLIB$$e2189a5.invoke(<generated>)
	at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191)
	at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:617)
	at org.saiku.web.rest.resources.ExporterResource$$EnhancerByCGLIB$$a1f407db.exportChart(<generated>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
	at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:205)
	at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
	at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288)