Debug empty $endOffset for http range

With CLUSTER_ENABLE_HTTP_RANGE enabled, Google Chrome asks for the total bytes range header "Range: bytes=0-". With this request header, the cluster gateway does not recognize end offset value and return this response header : "Content-Range: bytes 0-/19448241" which is not valid.
See the "Range" header RFC : http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35
and the "Content-Range" header RFC : http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.16
Tested on a .mp4 file (on dfsmysqli) with Chrome 23.0.1271.64 on MacOs X 10.8.2 from client and both NGiNX 1.2.5 and Apache 2.2.20 on Ubuntu server.
Merge remote-tracking branch 'upstream/master' into patch-1
Added stricter checking like suggested in https://github.com/ezsystems/ezpublish/pull/506#issuecomment-10550894
Corrected codestyle
Added final bytes support (eg "bytes=-500") see http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35
Merge pull request #506 from darylounet/patch-1

Fixed EZP-20170 - Bug with MP4 Files and HTML5 Video tag in a clustered enviroment
Debug empty $endOffset for http range.