inconsistency in handling of FOAMversion

Issue raised (or stumbled over) by @escrmic

The compilation scripts define Foam::FOAMversion based on the version information at compile time (eg, WM_PROJECT_VERSION=1612). Subsequent renaming of the version within the etc/bashrc (eg, WM_PROJECT_VERSION=1612.update2 or whatever) will not be respected in the internal findEtcFiles() lookups. This can lead to a slight dichotomy since bin/foamEtcFile will use the current value of WM_PROJECT_VERSION. Thus foamEtcFile and findEtcFiles() will potentially locate different version-specific user or site files.