IDE-1592 depend on bundles not features
Prevent simultaneous thread access to sdk manager data
Version 2.1.1 -> 2.2.0
Tycho 0.19.0 -> 0.20.0
Indigo -> Juno target
Updated copyrights
IDE-1557 refactored codes about descriptor helpers

- move classes about descriptors to com.liferay.ide.project.core.descriptor
- make class LiferayDescriptorHelper abstract
- new way to invoke descriptors' operation