...

1. failure at any point during the form upload to ssvm apache would return error to the user and DOWNLOAD_ERROR when the management server pings for download status.
2. polling starts after the success of GetUploadParams
3. current polling interval is 10000 ms 
4. currently it polls thrice to check the status. We may need to increase this. (is the current value 5 or 3?)

Agent Commands

1. DownloadProgressCommand will be used the check the download progress (from Management server to Agent)
2. DownloadCommand will be used to start the download(SSVM Apache to SSVM Agent)

API changes

1. new API GetUploadParams which takes all the params as the registertemplate/uploadvolume except for URL and  which returns all the required params plus a post URL to be used to uploadVolume/registerTemplate
   
   A sample request and response would look below
   request params: 

   name=lxc1
   displayText=lxc1
   zoneid=-1
   format=TAR
   isextractable=false
   passwordEnabled=false
   isdynamicallyscalable=false
   osTypeId=1b510c30-3352-11e4-aaca-a5c7f57670d0
   hypervisor=LXC
   requireshvm=false

   
   response params: { "postURL":"https://ssvmpublicip/upload/key",params:{"store":{"com.cloud.agent.api.to.NfsTO":"nfs://10.147.28.7/export/home/rajani/lxc/secondary"}, "hvm":false,"description":"lxc1","maxDownloadSizeInBytes":53687091200,"id":207,"resourceType":"TEMPLATE","installPath":"template/tmpl/2/207", "format":"TAR","accountId":2,"name":"207-2-09c78adc-065f-3dc8-9621-9e7a036d7dc9"}}
   
   

...

1. Download progress to the user (http://creativejs.com/tutorials/advanced-uploading-techniques-part-1/ )
2. split upload and join in apache so as to not hit browser timeouts
3. expires support for the post url to SSVM Apache