t64562: add test to demonstrate Content-Length bug large files

Apparently there is a Java bug on the server side that limits
Content-Length to a signed 32-bit integer (about 2 gig files).
The only place this seems to cause a problem is when reading
a file larger than this limit using vofs, in which case the file
length is reported as 0, causing an exception.
t64562: fallback to X-CADC-Content-Length in Content-Length is 0
t64562: address code review comments
Merge pull request #48 from edwardchapin/t64562

T64562: fix Content-Length bug PUT part was never a bug, only GET was.