Added option to use system Open Babel

It was already written

Change-Id: Iecaa9c922f34588880cf50f1762e6cc70c6f23a7
Removed debug line

Change-Id: I56eb2715bccab8a29399cd3900dfb2c761e9f09e
Merge branch 'optional-ob'

Change-Id: I2b9cb9e0df528afc9a91f3c4f40d261f9b3370f9