updatePomFIle should default to true for flattenMode resolveCiFriendliesOnly

[andham]

I ran into an issue where the parent/aggregating pom for a multi-module project didn't deploy the flattened pom to the local and remote repo. We're using flatten to substitute CI-firendly version properties. In that case it is very non-intuitive that the flattened pom for the parent is not deployed but only for the modules.
I suggest that updatePomFIle should default to true when flattenMode is set to 'resolveCiFriendliesOnly' (as it does if it is set tom 'bom'). I could even argue that it should be set to true as default for all flattenModes.