edit ad, fixes issue with queue square shown on preview, fixes error when preview is loaded without form parameter
added tolerance for OpenRosa servers that do not respond with X-Openrosa-Accept-Content-Length header
fixes issue with previews that do not have form parameter, edited ad
Revert "fixes issue with previews that do not have form parameter, edited ad"

This reverts commit 5522d84aca3b78c2dd30c82c279c98797e8b66bb.
Merge pull request #218 from MartijnR/master

fix for absent X-Openrosa-Accept-Content-Length header, fix for previews