CP-8866:Develop for Resource Statistic Feature on XenCenter

Based on the requirements draft and discussed solution, develop the prototype for Resource Statistic Feature part on XenCenter, that is, provide the export to Excel and CSV functionality with required data sets,by accessing the XenCenter cache.
Signed-off-by: Cheng Zhang <cheng.zhang@citrix.com>
Cheng -- from the exported sample data, the GPU resource report listed as the 4th part, is that doable to list GPU as the last part of the whole report? as thinking that GPU report is optional and sometime is blank.