Improve Eclipse setup

Only apply the Eclipse plugin to subprojects. This prevents the
creation of an Eclipse project for the root Gradle project which was
masking the Eclipse projects for all of the Gradle sub-projects.

Update .gitignore to ignore the bin folder created by builds in
Eclipse.
Merge pull request #11 from wilkinsona/eclipse

Improve Eclipse setup
Introduced @PayloadRoots annotation

Introduced the @PayloadRoots annotation, a composite of @PayloadRoot.
which allows users to map to multiple payload root element names.

Issue: SWS-864