springboot Allow project dependencies to be assigned to layers by their coordinates

This change adds support for including/excluding project dependencies in multi-project builds in custom layers in the layered jar built by the bootJar task. Project dependencies can now be included/excluded from custom layers defined in layered DSL intoLayer closures by using group:artifact[:version] patterns.

Comment From: pivotal-issuemaster

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Comment From: pivotal-issuemaster

@PaddyDrury Thank you for signing the Contributor License Agreement!

Comment From: wilkinsona

@PaddyDrury Thank you very much for making your first contribution to Spring Boot.