[Tom] #238 Rename ARTIFACT_VERSION to TRANSFICC_VERSION.
[Tom] #238 Rename ARTIFACT_VERSION to TRANSFICC_VERSION.

All of our jenkins and tf scripts use ARTIFACT_VERSION internally
but Jenkins itself uses TRANSFICC_VERSION (presumably because this is
a better name for a parameter) and then export this to ARTIFACT_VERSION.

To simplify things, I am going to attempt to standardise everything to
just TRANSFICC_VERSION


TransFICC/transficc-functionality