Fix ImageAcquisitionDate parsing for DeltavisionReader

Previously, the last block of parseLogFile() was always escaped and the creation date was being filled as a parameter/key value in the global metadata. This commit restores the validity of the last block and fixes the
joda DATE_TIME pattern.

Noticed while testing 5.0.3-rc2 search functionality /cc @jburel @mtbc. This change will certainly not make it for 5.0.3.
Next items:
- [ ] check this PR against the deltavision repository
- [ ] check the import works as expected
- [ ] decide how to handle log files not matching the pattern (`Wed Sept 7 17:21:39 2011`)