Support for Spring Boot

[monsieurhess]

Right now starting an Apache Felix OSGI Container is supported for a standalone app and for a WAR webapp. Many applications today are developed with Spring Boot as standalone app framework. For these cases there is right now no support to start an Apache Felix. This support shall be added now. Therefore 3 packaging layouts will exist then for a bndly application:

• Standalone JAR
• Embedded WAR
• Embedded in Spring Boot Standalone JAR

To accomplish this, the Environment interface will receive further abstractions and the start sequence for Apache Felix will become more generic.
A Spring Boot app will not look in the file system for bundles to install. Instead an explicit list of bundles to install will be inspected. This list will be generated during the provisioning of the bndly application.