Use OCE libraries rather than OpenCascade because of licensing.

Refs #10616
Fix typo in OCE requirements

Refs #10616
Merge remote-tracking branch 'origin/master' into feature/10616_use_oce_packages
Merge pull request #76 from mantidproject/feature/10616_use_oce_packages

Use OCE libraries rather than OpenCascade on RHEL/Fedora