Add build log to release description

[TheAssassin]

I would appreciate if there was a link back to the Travis CI build log in the release description.

The functionality appears to be implemented, looking at the code, I am not sure why this isn't happening, though.

@probonopd could you please have a look why the URL isn't appended to the description?

[probonopd]

There is a check if [ ! -z "$UPLOADTOOL_BODY" ] ; then which I think evaluates to false, causing the log not to be appended. The variable and if clause was introduced in 494d5a5 - could it be that it needs to be if [ -z "$UPLOADTOOL_BODY" ] ; then?

[TheAssassin]

@probonopd when using -z to check whether a variable has set, there must not be quotes, IIRC.
See also 494d5a5#diff-41c2c2edf223528193cd5163683cad3dR42.

A more straightforward (bash-only) syntax would be [ "$UPLOADTOOL_BODY" != "" ].

[TheAssassin]

Also, I think you're right workflow wise, the ! negates the value of the check, which is not desired here.