[1.3] Updated DataUtil::formatForOS for absolute paths in windows

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | -
| Fixed tickets | #627
| Refs tickets  | https://github.com/zikula-modules/Content/issues/135
| License       | MIT
| Doc PR        | -

On windows test environments an absolute template path is not working currently. Compiled template gives errors, see ticket https://github.com/zikula/core/issues/627 for more information.
During the change from 1.3.4 build 12 to 1.3.5 this part was changed in https://github.com/zikula/core/commit/9e74470be36db99cc185a699fd6102e95ba634e0.
This update reverts a part of that udpate.

Removal of the : in the preg_split makes that win test environments don't work with absolute template paths any more. I cannot see a side effect of adding this : back in the preg_split.
It does solve windows testing for a number of modules.

ping @cmfcmf can you check as well ?