NEXUS-6358: Adding composition info to describe output
[NX-347] Add support class for capabilities without configuration
Merge pull request #422 from sonatype/NX-347-capab-without-config

REVIEW: [NX-347] Add support class for capabilities without configuration
Merge pull request #419 from sonatype/NEXUS-6358-describe-composite-items

NEXUS-6358: Adding composition info to describe output
POC: switch to extender approach for starting/stopping plugins, reduce webapp to thin bootstrap layer
Set TCCL so javax.mail can find its implementation
Use global index for the main extender bundle
Add secondary index in nexus-extender for embedded components that don't already have an index (namely sisu-resource-scanner, but there may be others)
Can go back to local index now
Enable indexed-scanning of plugins/bundles
Use OSGi services to communicate between bootstrap and extender
license:format
Karaf/Jetty bootstrap bundle and assembly
Example custom karaf assembly
Make OSS edition a fragment bundle
Don't expose internal guice packages
Update to Apache/Felix 4.4.0
Provide nexus-start and nexus-stop shell commands (will be replaced by features at some point)
Add README to help get started