Expand on installation options

Include configuration for extension activation via pom.xml.
Add link to artifacts in Maven Central.
Add handling of multiple remote dep mgmt poms

- Add parsing of comma separated list of remote depMgmt poms
- Add new integration test for this feature
- Update README for new feature
- minor refactor of ITs
Minor refactoring integration test
Add error handling for bad remote pom GAV
Refactor to simplify package structure
Allow multiple plugin management poms on the command line using a comma separated list
Add test to verify that extension can be used via pom extension
Update version for 1.1.0 release
Update to 1.1.1-SNAPSHOT