Child plan should not run if it does not have a branch plan that matches the parent

Bamboo will currently run a child plan whenever the parent plan completes, regardless if the child has a branch plan configured for the branch the parent just finished.

In order to support having a "master" plan that then has many children that do different things depending on the branch name, Bamboo should have an option to respect the child plan branches.

This has come up because we have multiple platforms to QA on, but only need to run those QA jobs on some subset of parent plan builds which can be identified by the branch name. E.g. that branches containing the string "project1" in their name should trigger child1 after building, and branches containing the string "project2" should trigger child2.