Blender Git Loki

BKE_appdir: log details about path lookups

These were printf's, disabled by a define that could be uncommented.

Use logging since this can be useful when investigating any issue
with paths not being found at the expected location.

Without this any problem finding app-templates, Python's installation,
icons ... etc are quite difficult to troubleshoot especially on systems
without access to system-call tracing.

To use this run:
blender --log "bke.appdir" --log-level 3