put OGS logs into cwd instead of SGE_BATCH_LOGDIR or ~

These can contain useful information and it seems to make sense to put them in the same dir as the other logfiles.

Things are a bit messy due to limited options of the `sge_batch` executable (also see issue #38).

Matthijs has suggested potentially combining these files if this would be more readable.

Do we need other options for logs?  Advice appreciated.