Fixes for velocity template caching and Update Checker Job

Velocity Templates:
* activate inline scope for velocity templates
* make Contentconnector templates serializable
* fix caching of velocity templates in VelocityTemplateManagerFactory
* VelocityTemplateManager now tries to get a cached velocity template from the VelocityTemplateManagerFactory 

AbstractUpdateCheckerJob.java
* stops now checking objects for update if it detects that the current thread was interrupted